Thats a good idea! Not sure I am up to it though 
With a decent 'razor saw', a drop of superglue (well maybe a drill and a pin, too ;-) ) and a tiny amount of greenstuff, I think you'd be fine :-)
I've been fiddling around with swapping hands on some of my LotR figs, and it's just amazing how easy 'swap-conversions' are when using the right tools. I was amazed, anyway, as I'm really not a 'modeller', but was quite satisfied with the results (and I'm a hard man to please, as i have a strain of perfectionism in me)....