My understanding is you can't (shouldn't) have two computers hooked to one FW drive. Just not a good idea as it "confuses" the drive as to which machine controls it.
If you're constantly working on the same projects with two discreet machines, here's a suggestion. Why not start capturing your media in an offline or lower resolution? For example, I have a current project where full res stuff takes well over 130 gig of space. I captured using the MPEG 4 codec - at the 720X480 size- Footage only required 20 gig of space. All footage plays in real time with no rendering required - same with titles. I can now work on the project (edit/titles/composite/whatever) without taking up the 130 gigs of space. Also runs a bit faster due to the lower data rate of the MPEG 4. (So i can edit on my powerbook vs having to plug in the FW drive)
You then "clone" the media files to your boss's setup. Now you both have identical media offline files. The only thing you need to exchange now are the FCP session files for the edit. Once you have the final edit figured out, you just recapture footage at high-res, render, output and you're done.
This also gives the added advantage of having 5 or 6 good sized, ongoing projects (at low res) on a single external FW device. Having 2 media drives cloned (One for you, one for your boss) is also a safe backup strategy. If your drive dies, stuff is on the boss' drive. If boss' drive dies, stuff is on yours...
good luck