can I connect it to the alternator housing?

 

I wouldn't do that. Its poor practice.

Your negative battery cable should always go to the engine block/head. The rest of the car needs a good ground source too, not just the alternator.

 

Why would you want to? The largest current draw by far is the starter motor. The negative cable needs to be bolted directly to the block to minimize resistance and thus prevent hard starting. Any additional bolted joints between the cable attachment and the starter will only increase resistance and eventually cause hard starting. The factory location is typically at the front of the block under the PS pump, usually on a stud that bolts directly to the block.

 

I agree with what has been said. If you feel that the alternator needs better grounding, run a separate wire to better ground its case.