Any specific reason you chose ISboxer? Is this the software that lets you run multiple instances on a single computer? I forget which one enabled that.

I tried tri and dual boxing for a while (never got past L17). Just couldn't be bothered with all the gathering and quest accepting/turn ins. I think I have just gotten really lazy since all the changes in WoW that made boxing easy. However, I think part of my problem was also the classes I chose. Some class combinations were definitely better than others. So, I highly recommend putting some thought into that if you're not choosing the same class.

For boxing, I used 2-3 computers and a wireless keyboard synced to all computers. I never bothered to work it out with Keyclone or any other software.