Neither type of defense weapon can generate recoil (I just tested it). So it looks like you'll have to use Egeras' suggestion.

Also, remember that you'll have to check "detonates at end of life" and "blast affects player."

However, this will probably cause a slight problem in dogfights: any ship that point defense shoots at will also trigger the auto-dodging effect. This could make fighter battles... funny. There may have been a way to sidestep this, but the "don't fire at fast ships" flag does not affect PD weapons (again, just tested it). It will still work though.

Of course, Qaanol's probably found a way around that too.

Hurray! It works! Just as Qaanol did, I implemented it for TCTC. It works, although it sometimes goes weird when the enemy is travelling faster than its shots.

Here it is, in all 2-colored glory!