Powerbook 12" and triple display setup possible ?

Hello,
has anyone ever tried or knows of a solution to hook up both a VGA and
a DVI display to the mini DVI port on a Powerbook 12".

Is there a chance of overheating the powerbooks graphics processor ?
The manual states that you shouldn't use an external display when
you're not connected via your powerchord....

In theory it should be possible to split the signals, it would be okay
if both external display display the same picture...

Thank you very much...
bye Fred