Parallel compression on the 500?

Is there a way to simulate parallel compression on the mpc500? Can I program the audio level of a pad over time?

You can but for samples not the actual tracks themselves unless you resample the parts as stems onto the pads.

I'll begin with an easy example to do it.

Say you sampled a drum loop that you wanna NYC (thats what we call parallel compression in Brooklyn). The drum is on Pad1 now. Now go to TRIM mode and use the Copy feature to copy the drum loop to Pad2. Now with Pad2, go to EFFECTS mode and compress the shit out of it, talking hard compression. But pad1, do nothing. Maybe some EQ if you like. Then play both pads at the sametime and viola! Parallel compression.

Ok, great..

I actually meant sidechain compression, sorry got a little confused
I want to duck a bass sound in sync with the kick drum.. Is there a midi cc for pad volume that I can use to vary the volume over time?

I'm not a MIDI user but the same steps apply for ducking but with the copied sample, lower the volume to 20 or 30.

Ducking is not complicated, its the same method used at supermarkets, you listen to the soft jazz then suddenly you hear "Tom, got a call on line 6, Tom, call on line 6." With the music pushed to the background and then sounding normal again after the speaker hangs up. Thats ducking but new cats applied it to beats and the rest is history.

'Tom, got a call on line 6, Tom, call on line 6.'

Well by ducking I meant that the everytime the kick drums plays a bass sample is pushed to the background leaving more space for the kick..

You can sort of fake it.

What I do is putting the kick with heavy LF and the sample I want to duck into the same compressor, fiddle with parameters until I got it "bumping" and then layer normal kick on top of it.