Don't know if you've resolved your problem yet, but I do the same thing here at our office (current version of Outlook for Mac blows).
I was able to import e-mail lists on a limited basis by doing this: log on to Outlook on a Windows workstation, and export your list as a text file (probably .csv or something, I don't remember). Then import that into the OE 5 address book. You'll probably have to clean it up a bit -- mine had extraneous quote marks all over the place.
It's quite an imperfect solution, but with a little time you can make it work reasonably well, and at least better than the current version of Outlook.