yeah, that's my thought as well. just wondering if there is an easier way.
i've decided its not worth it, but here's how i would go about doing it (for the sake of anyone reading up on this at a later date) ....
in IP, have a datafield called "write" and promote it as a column in the doc library.
then, in a sharepoint workflow (create/change events), update that column with the user names of the individuals you want to have write access to it.
back in IP, create a conditional formatting on the button that checks to see if the "write" column contains userName().
that *should* more-or-less do it.
thanks again Qazi.