In your version of B2, in the Write/Posting page, you can select to CLOSE or DISABLE comments for each particular post you make.

Re a Global method, I'm sure it's just a hack of an existing php script but I'm not sure

Thanks John, I already close the comments on some of my post but now there is realy to much spam, I want to disable all the comments for a while.

Check/search "Comments" as there are other posts on the subject
I just hope they get the new version out soon as spam is making it a real pain