What I used to do(been working with mostly real drums lately) was to find fills in the EZdrummer library and drag/drop several onto the timeline, but well past the end of the song. I would then pick and choose which fills(and often just small pieces of them) and copy/paste into the song where needed.
In case this sounds a bit cryptic, some of the fills from the library are a full measure and 2 measures, but I may only need a half measure fill
