It's a straightforward contradiction in terms. An amp for an electric is designed to add colouration and tone etc to enhance and amplify the sound of an electric guitar. An amp for an acoustic guitar needs to be distortion free, massive dynamic range, clean and have a flat frequency response.
There is an easy way to do it however. Get a Bose compact:
http://www.bose.com/controller?url=/...pact/index.jsp
You can play the acoustic directly into it and it will sound amazing, and just get a modeller to use with the electric. The sound of the Bose is so flat (as in frequency response not overall 'tone' or sonic 'goodness') that it works just great with a modeller with amp and speaker sims dialed in. I suggest the Boss GT8 as these are available quite cost effectively S/H on Ebay, and they sound great. So, the Bose package is ultra light, ultra quick to set up, and has excellent spread.