I'm not quite following your request, gogol.

Are you asking for your setup to work while your physical keyboard is open?

If so, maybe trick the tablet to believe that it's closed.

Either:
gconftool -t bool -s /system/osso/af/slide-open false
or
gconftool-2 -t bool -s /system/osso/af/keyboard-attached false

If you're looking for the keyboard to pop up whenever you want it to with a hardware button, you'll still need to have the cursor located at some place to input text anyway.

Are you asking for the same behavior VNCviewer does?

Clicking the middle D-Pad brings up the keyboard with this app.