I am fairly sure you can go beyond 255 characters using ISBoxer.

I have not bothered with dual specs yet however if I was going to try it myself I would probably bind a key map to switch specs and also load a new set of key maps at the same time.

Something like:

Code:
Hotkey ALT+CTRL+SHIFT F12

Step 1

Actions:
1. Wow macro -> /usetalents 2
2. Spec 2 Map on
3. Spec 1 Map off
4. Popup Text -> Switching to spec 2

Step 2

Actions
1. Wow macro -> /usetalents 1
2. Spec 1 Map on
3. Spec 2 Map off
4. Popup Text -> Switching to spec 1
Hope this makes sense to anyone familiar with ISBoxer :P

Bah too slow at posting!!