lots have done it and is fairly easy. you just need to cut the opening and mount them down securely and run wires to them. the issue is that they will project better than the side panel mounts, but you will loose some of the sound stage doing them there. you'll get better overall sound using the stock location.
also if you are wanting to use those along with the existing rears (using 6 speakers) you will need an amp to power them as the head unit won't be able to do the extra speakers properly. or you can just get rid of the stock rears and run the wires to the deak.
2010 Volvo C70
2011 Harley FLHTK
Midwest Crew #22