This example is based on Logic Pro but the concept is very similar in most other sequencers that have external sidechaining (key in) .
First you still need to equalize and compress both the kick and bass separately as usual. The sidechain compressor is an extra compressor you add at the end.
10 Step Guide
1. Output the kick sample to a bus (e.g. Bus 1). The reason being that Logic can't sidechain directly to an audio instrument, only to audio channels or busses. So this is a workaround.
2. Insert a Logic compressor at the very end of the chain on the bass instrument. Remember this is an extra compressor for the sole purpose of sidechain compression. Be sure to use the default settings of the compressor (very importantly: no Autogain, no limiter etc.)
3. Set the compressor's external sidechain (the Logic compressor also has an internal sidechain via the expanded options - ignore that in this case) to Bus 1. You set the external sidechain input in the upper right corner.
4. Set the attack to 0 ms. You want that bass ducked immediately to gain headroom. The attack of the kick will act as all the punch you need in the mix for that split second when the bass is ducked. This is partly a psycho-acoustical phenomenon.
5. Set the knee to hard (0.0). You want the peak of the signal to be the trigger, nothing else.
6. Set mode to "Peak". For the same reason above. RMS mode is sometimes used for delay ducking, which is slightly different from kick/bass ducking.
7. Set the gain to 0.0 dB. You don't want to change volume otherwise, so set it to unity.
8. Set a ratio between 4 and 10. How much depends on how much ducking you want. A ratio of 10 will almost remove any bass attack which might be just what you want.
9. Set the release time depending on how fast you want the bass to stop ducking, usually fairly quick, e.g. 20 - 50 ms. Longer times will make it pump more, which could be a desired effect - so experiment. Auto release is optional but primarily recommended when used in combination with more varied rhythms and note lengths than a standard kick/bass pattern.
10. Set the threshold according to level and trigger point for the ducking, use your ears and look at the meter. About 3 dB of gain reduction is usually more than enough. Remember that in this scenario you just need the very top of the signal to react, so don't pull that threshold down too far, you'll gain nothing extra.
Not only can it make your track sound slightly faster and improve perceived timing, it'll probably make it a good 2 dB louder without any noticable side effects.
The closest you get to a magic increase in loudness potential in dance music.