BIOS upgrade is not possible from within dosemu/dosbox or wine. Even if it writes something to the bios chip, there is a chance it might corrupt the data here - I wouldn't take the risk
I managed to create a bootable ISO, based on the N200 0867 bios update floppy image, with 3.03 bios rom. To flash the BIOS from DOS floppy image, a quite "fresh" phlash16.exe is required. Much newer, than the one provided by lenovo for 0867.
I have downloaded and run, as Administrator, the 68et35ww.exe BIOS update file, but no files appear in the directory created. When run a second time, however, Vista asks if I want to overwrite the files. As an experiment, I ran the previous version, 68et35ww.exe, just as I had the latest one. It extracted everything just as I would expect it to. Any ideas?