There are ways to do this. I assume you are talking about RealDrums? The easiest way to do it is to keep re-generating the drums until you get the drums you like. Then freeze the drum track.

Another more complex method is described in this post...

http://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=99596&Searchpage=1&Main=15661&Words=.txt&Search=true#Post99596

More info about the RD txt files can be found in the user manual.

RealBand can also be used for editing the drum track.

R