Thanks rivviepop. This sort of fixed the problem, I was able to enter text using "type" but it was very slow to respond, and backspace only sometimes worked.
Annoyingly, I wanted to be able to attach to my screen session running irssi, but was unable to do so.
It seems crazy that the only alternative costs £50 / $95, I wasn't aware of the cost and unavailability of applications for blackberry before buying one. I love it apart from that to be honest.