hi,
I have just finish my WiiPen, and I have some ideas maybe good for you.
I have made My pen with an old USB mouse.
The goal il tu put the right clic on the pen .
1st, I take an old mouse and
I removed the LED position and the micro switch of the wheel and the IR led of the wheel
and use the Micro Switch and the IR led for the pen.
I plug them on a little sheet. ( I'm right handed, and I put the led at the left side for better reception ( and with a better angle )

I use the power of the mouse

but for a better reception and smooth, I change the angle of the led

and it's work perfectly :oD
Next time... the Right clic on the pen...