Yes, it can be done.
And unlike what is suggested in the Lenovo article referred to, it is NOT necessary to be running in "Optimus mode". You can in fact be running in "discrete graphics" mode to accomplish this just as well.
I don't own a dock, but can run three screens in the basic non-dock 3-monitor configuration using the laptop screen and two external monitors connected directly to the W530. One monitor is plugged into the miniDP connector, and the other monitor is plugged into the VGA connector.
And all three displays are handled by the K1000M through nVidia Control Panel (and "discrete graphics" set in the BIOS), with a Windows extended desktop running across all three.
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I DO NOT RUN IN OPTIMUS MODE EVER! I am plugged into AC power virtually 100% of the time, and do not run on battery except in the rarest of situations (and even then I run in "discrete graphics" mode, not worrying about having only a few hours of possible battery life before needing to recharge). I have no use for the built-in Intel HD graphics and opt to use the K1000M for best-possible graphics 100% of the time.by setting "discrete graphics" in the BIOS.
Note that in "discrete graphics" mode, you can install the standard retail nVidia graphics driver (latest one for K1000M is 341.21). I do not use the Lenovo-provided Optimus driver (which includes back-level old nVidia driver along with Intel graphics driver). The built-in Intel graphics hardware is essentially gone from the machine and does not even appear in Device Manager.
So the answer to your question is YES, all you need to do is plug the third display into the VGA port of the W530, and after enabling the third monitor through nVidia Control Panel you then configure your multiple display "screen resolution" in Windows, in order to extend the desktop across all three displays (i.e. across 2 and 3).
Note that it may take a bit a struggle and several re-boots and rearranging monitors in GUI pictures, in order to finally get your 3-monitor setup to be properly independently configured and arranged as you want, with the proper resolution on each one. But eventually, I "emerged victorious" for this experiment. The above 3-display setup now mostly "sticks" across re-boots, with 1920x1080 laptop screen on the right as #1 and two 1920x1200 additional displays to its left as #2 and #3.
But for some reason, some re-boots cause "instability" and mishandling and misarranging of the three monitors, and I have to play around all over again to get it to look right and work properly again which I eventually do have success with. But this "stability" may only last across another re-boot or two before again getting scrambled and requiring fixing again. Annoying, but the answer is simply not to re-boot once you get it working if you don't want to have to fight with it again.
So, although running with 3-monitor under control of the K1000M is obviously possible, there appears to be just a bit of some "delicacy" and irregular behavior across re-boot. It's not clear to me whether this is due to a Windows 3-monitor issue, or to the nVidia drivers driving 3 monitors from the one K1000M, or perhaps from the W530 hardware and providing erratic sensor signals at boot time from the two external monitors connected, or what.
But whatever the cause there definitely seems to be a bit of a "delicate situation" you may have to put up with if you do need to re-boot while in a 3-monitor setup. But once you get things configured properly as a 3-monitor setup in a currently booted Windows session, simply continuing to use it in that same Windows session works perfectly and is rock solid with no anomalies at all. So just don't reboot, and you won't have a problem. (I don't know if SLEEP/WAKE-UP will also cause similar irregularities as I didn't test that, but I'm guessing it probably WILL cause similar anomalies that will require your correcting them... so again, don't put the laptop to sleep if you don't want to fight with the 3-monitor setup at wake-up time.)
Note that my normal operational setup is NOT to run with a 3-monitor extended desktop for the W530 (although it's certainly possible as is plainly seen). I honestly don't want to be using the laptop screen at all when I have a large 24" 1920x1200 external monitor available (as I generally do). So I run just with the one external monitor active in a single-monitor setup, and do NOT also use the laptop screen (as part of a 2-monitor extended desktop) at the same time.
So I usually just run with one of the two available external monitors as the one-and-only monitor #1 for the W530 and the W530 laptop screen OFF. The laptop comes on automatically if I have no external monitor connected (i.e. if the monitor is still switched to my HTPC), but goes off automatically if the external monitor is connected.
And as you'd expect this external monitor that I use (through a multi-input switch in the monitor itself) is actually one of the two [above] monitors I norrmally have connected to my desktop HTPC machine. So when it's being used by the laptop it's not available to the desktop HTPC machine. The laptop is physically on the same desk space as the two monitors live, and selectively uses one of them through the monitor input switch on that monitor. In normal state while I work on the laptop and use the one external monitor connected to it via miniDP->DP cable, I am also running the 24/7 HTPC and watching TV on the second monitor which is still connected to the desktop HTPC and actively selected to it for input.
But for this particular experiment to confirm that it COULD BE DONE using K1000M only (i.e. "discrete graphics") and does NOT REQUIRE OPTIMUS MODE, I used both of the two monitors from my desktop PC as laptop monitors #2 and #3 (through their multi-input switch capability), with the W530 laptop screen as #1 in the 3-screen setup.
And sure enough, it's now proven that YES IT CAN BE DONE with just the K1000M controlling the laptop screen as well as the two external monitors connected via miniDP and VGA connectors on the W530. No dock needed, and no Optimus mode required.
