First find your song's (BPM) beats per minute, then calculate your attack
and release times.
Heres one way you can use a compressor to artificially pump an 1/8th note bass line on every quarter note. First set the attack to a 1/16th note and the release to a 1/4note-1/16th note. For a BPM of 95 in this case set the attack to 158 ms and release to 632-158 = 474 ms. This should let the 1st transient through (approx 1/16th note in length) then clamp down on the rest of the 1st eighth note and the 2nd eighth note and then be fully released by the time the 3rd note starts. Basically what you get is the 1st half of every other 8th note goes through untouched thus creating a pumping effect. This is a great way to add ear trickery and take your mix to a whole new level.
