I finally have a working set up with bip and bitlbee. I'd previously used the versions packaged with Ubuntu. This turned out to be a bad idea. The packaged version of bitlbee didn't have Twitter support and the packaged version of bip would crash any time it was pointed at bitlbee.
Short version of the story is bip 0.8.6 and bitlbee 1.3dev are now installed, both compiled from source code and both playing nicely.
However, I did spend most of this morning trying to get XChat to autoconnect to bip (and bitlbee/Freenode/OFTC/757 beyond that). Finally figured it out: you shouldn't add the "quote pass name:passwd:connection" string to the autoconnect command field. Instead, just add "name:passwd:connection" to the Server Password field. If you're editing the servlist_.conf file by hand, your server will have a "P" line that looks like:
I'd been messing with the "C" line and not getting anywhere. It wasn't until I was wading through the XChat docs that I realized that this might be treated as a password string. Tried it and it worked!
Why is it that the simple things take all day?