youd be surprised at the number of explosion scripts and addons that have been made and there are plenty around. a flamethrower that hurt people might be tougher.... anyways im not a hardcore addon or script maker, i can just do moderate stuff
if you want an example of a fire script, you can see one in the resistance campaign or there is a thread that contains a good script that is used to make barrels explode and burn but it can be easily modified to do the same to men. this would help in making the bodies burn like you mentioned... ill post the thread when i find it
also, btw, flame and explosion scripts have a nasty habit of creating lag, which is never good esp. in MP