Well, boundaries that hinge on someone else doing something are the toughest to enforce. In fact, when you frame a boundary on "you do this, or I will do that" it's really more of a rule than a boundary. You might want to look at that. Go deeper. What is the reason you want him to find a job? Maybe there is a way of reframing the boundary so that the action is yours to take, not his.
For example: "I will not support you while you drink and refuse to work, if you do not contribute your share to the household expenses, I will find a place to live on my own where my only expenses will be mine."
This may not work in your situation, but if you look at your boundary and make it more about you and less about him, you will find you won't feel so helpless in enforcing it.
L