I have a Schriber external mono mic which, when plugged into the gl2, records only on the left channel....
I was wondering if I'd be able to splice together a cable which would allow the mic to record on both channels (although I know that the sound would still be mono)

I was thinking something along the lines of using a stereo cable and splicing it into an XLR head...

Does anyone have any experience/advice for this kind of 'experiment'??

Thanx Ahead

Of course you can do this, but to what gain? Using a mono mic split to 2channel can lead to phase issues, where of course, you have 2 channels of identical sound. There are several brands of Y connectors that will split the mono to dual channel. Radio Shack sells them, no wiring needed.
Keep in mind that with a 2 channel adapter, you can connect 2 external mics to the cam, giving you 2 separate feeds, ie; one for interviewer, one for interviewee.

The reason is when I listen to some recordings on my home stereo speakers I only hear one speaker, naturally, but periodically I hear static sound bits coming from the other speaker. So I want to eliminate that (by getting the same sound from both speakers) and I just wanna record on both channels for the hell of it....

So buy a 1/8 mono to 1/8 stereo adapter. $4-$5 at good old radio shack.