A Test Board?
 

Would it be possible to install vbulletin as a test board on a different domain?

yes!

just keep it in testvb folder and locked via htaccess.

No. It has to be on your domain. Otherwise, veenuisthebest is correct.

locked?
1. How would i do that?
2. If i done that i wouldnt be able to access it would i?

What they meant was that you have to have it password protected.

i think i get you.
You mean install vb in a sub folder & password that folder?

Didn't they just say you can't allow registration.

There would not be much testing if you exclude registration. Just invite a group of members from your live board to test functions out.

Password protection is different than not allowing registration. You may leave registration on (in fact, you should test that when changing your board), just use htaccess to keep it from being accessed from anyone you have not given the password (and url) to. It should be used solely for testing purposes, not as a secret board.

vBulletin License Agreement

And the relevant clause: