Having seen this link yesterday, figured it was worth a go - just modded my RH shifter in 15 mins, works as it says.
Basically, it gets you the 2 shift finger release featured on XTR, by cutting a bit of plastic from the lower housing cover. Looks like Shimano use some similar parts, so have to block off the extra shift with the bit of plastic.
Usual warnings - not an official mod, warranty void, you might cock things up, it's not my fault etc...

