Well the pedals don't cut it wright, you're even better off with a good patch...
Still not close to a real guitar, but I might be too critical since I am a guitar player myselve..

Still it is possible to do with software like reason/reaktor..

If you like to find out how much can be achieved with emulated guitars on software, you might cheque out Rick Richards...
He produced an entire cd with reason.
Oh, and he has a unique style, not for the faint of heart though ( I love it)
http://www.progtronic.com/

Fred