Programs are kits+midi loops. I bet you will find kits make from their samples if you look it the kit browser
You can load any of the pads in SD3 with other instrument definitions if you wish. To load an instrument, right-click on the drum, cymbal or pad in the drumkit view or pad in the mixer view. That will allow you to create the drum kit you want, then save the kit (or program if you want to save the midi loops with the kit).
If you need more drums you can always run more than one instance of SD3