That's not supported, but here are some things you could try: 

You can try just changing the required version on this line at the top of the file:

Requires at least: 3.00

We don't test with previous versions, so it may or may not use functions that aren't available in v2.65.

If that doesn't work you can email me directly and I can send you the previous version v1.01.  

Hope that helps!

Is there any way to make the login/signup with twitter v1.02 add-on work with cmsB v2.65 (Build 1122) ?
(Immediate upgrade of the cmsB is very difficult right now...)

Karls