yes, it is possible. i just plugged my optical drive into one of the SAS connectors using a standard SATA cable and it reads and functions perfectly. you'll want to install all 5 HDDs on the SATA array, then any optical drive(s) can go on the SAS array.
update: i just installed a single SATA HDD on the SAS array successfully so it looks like you can install any SATA device on any of the 10 available connectors. the SATA drive had to be flagged as 'online' using diskmgmt.msc to get it to show up in windows. however, i still recommend using the hard drives on the SATA controller and optical drives on the SAS controller.
on a side note, i benchmarked the drive using both the SAS and SATA controllers and speeds were identical.