Get a registry editor for your touch pro2.
Next, edit HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shell\Rai\: DEFBROWSER (Had to put a space between : and D because it kept making the emoticon
, but in reality there should not be a space.)
When you choose the : DEFBROWSER there will be options to change some values.
The value that has the file path leading to Opera or PocketIE, whichever is your default, should be changed to the file path that leads to your Opera Mini install.
For example, mine said "Windows\blahblahblah\Opera9.exe or something like that.
It now says "Program Files\Opera Mini\jbed.exe" and the quotes do have to be there or else it won't work.
But like I said, right now it launches Java and then you have to actually choose to launch the Beta from there. I've got no idea how to change that from happening.