I'm sure it is possible. You can do almost anything to a car if you are willng to throw enough money at it.
The Dodge Charger as well as its stable mates the 300 and Magnum only comes as an automatic. Chances are it would take some work to find a manual transmission suitable then quite a bit of engineering to get it installed and working correctly. Perhaps one of Dodge's truck transmissions would bolt in; that would be the first thing I'd check into.
If you do this conversion you will probably be the only guy on your block with a manual Charger (and perhaps in the whole country).
yes it is possible to swap your automatic transmission for a manual. but, you said you were looking to upgrade with mostly bolt-on parts. just replacing your automatic with another automatic is a major task, but switching to a manual is going to be double the headache. unless your loaded with money that is, then you can just drop it off at the dealer and tell them what you want. for all the trouble you'll go through, it just wouldn't be worth it. finally, unless you just like driving a manual, the performance gain isn't worth the hassle either.
It is possible but it would be a huuge hassle not to mention expensive as hell.