You mean by default? That's coded into the app, and you'll probably need to get the developer to make that change.
If you meant that once the KB comes up how to show the T-9 style keypad, Depends - Multi-touch KB or Swype?
On the Multi-touch KB, I haven't seen it - you just hit ?123 to get symbols and numbers, but it is not the T-9 style keypad, it has the numbers across the top. The equal sign is, however, directly available from this mode as well.
If you're using Swype. you press SYM then Shift and finally the new 123 that appears - that gives you the t-9 looking keypad.