Most housings have a cold shoe mount. I've used that. Currently, I attach a third arm to one of my strobe arms. Downside is that sometimes I have to hold the strobe arm still while I adjust the light to avoid moving the strobe. You can get a three way clamp for attachment at the strobe arm joint or you can use either a ball type arm or a flex arm in the cold shoe mount. FIX makes a cold shoe mount with a Sea & Sea type connection that works with some lights, others have ball/clamp or flex mount options. A lot depends on which light you use.
