Welcome to the forum Ronnie.
Since I don't know how experienced you are with sample replacement let me know if you have any questions.
If I understand you correctly you are asking if you can take a finished song and replace the acoustic guitar sound. My short answer to that question would be, probably not.
Does drumagog actually do that though? I thought it could only do that to drum tracks before they are mixed down with the rest of the instruments. If it does do that I could see it being a pretty inaccurate effect seeing as how it would have to deal with any percussive elements of any other instruments (like the pick attack of a loud guitar).
But back to your question, replacing an tonal instument that can play multiple notes is something that DSP processors have not yet tackled completely. There are ways to get semi-accurate results, but not from a fully mixed song. You would need access to the multi-track project and be able to treat the guitar by itself.
First you would need a polyphonic Audio to MIDI converter. We actually had a discussion about a product that claims to do this a few weeks back.
http://forums.gearwire.com/oscillato...ght=audio+midi
Assuming the product can do all it says it can you would then need to feed that MIDI into a synth or sampler. I would reccomend a software sampler that either has acoustic samples or that you an add too.
Dan
edit: sp