Its a bit of a faff.. but here's how you do it!
>Scroll to the bottom of the thread
>Tap on the Subject Line
>Click Previous
>Click Next
>Tap in the Message box exactly where the first character would appear
>Type Message
Only problem is that it locks its self in Caps lock so you have to press shift in between every character... unless you dont mind shouting!
(i cant take credit for this... someone on mkiv put up the how to!)
Rich