Hello 

Yeah, you can mod it to RGB.  I guess you're in the UK because of the posting time, so I'd guess you want to output it in scart.
It's a bit of a mission, not because it's hard, it's just quite involved.  You'll have to make an RGB amp, which is just a bunch of components on a breadboard.  I screwed up my last one, because I didn't realise electrolytic caps had directionality (yeah, I'm an electro-noob too!), but aside from that, it's kind of going alright.
You'll also likely need to make up a scart cable, which shouldn't be too hard.  I've found an actual pre-made cable hard to come across, so I would say get a scart to scart from a pound shop (but make sure it has at least 8 wires inside it) and then get the connector you need from eBay and solder it on one end.
Here's the diagram for the amp 
http://www.gamesx.com/grafx/pce_rgb.jpgand here's the guide I'm following: 
http://www.mmmonkey.co.uk/console/pce/rgb.htm although he cheaps out on the amp side of things.
If you need a hand, let me know.  I might be able to help you out with some of the parts too, as sometimes you get like 100 resistors for £1, and I don't need them all.  some things like the transistors and some caps I only have 10 of though.
But whatever, I can give you a shopping list if you decide to go ahead.  There may also be a cheaty kind of way to put all the bits in a scart cable, but I wouldn't trust it.