Try starting a home club and give him the ID and the password. Be careful though, as all home clubs need to be approved based on a description you give when creating it. I doubt they'll approve something like this just so 2 players can play with each other.
Another thing you could do is register to a single-table SNG and give your friend the tournament ID. Tournaments can be searched via ID on PokerStars (Ctrl+T in the main lobby) so he can very quickly register. If you can do this within a few minutes (using IM there's no reason not to), then it'll work :) .