Help getting 800 members into 1 group

Hi Stackideas

Can you please help me get all my 800 registered site members into one group?
http://finalbug.net/groups/item/2-bug-all-members
I have attempted to do this but frankly it is next to impossible to do this manually.
I gave up after I got to 399 members and then had new members registering at the same time…
Sorry to say this but the way it is currently set up is insanely difficult.
Maybe a script or something

thanks in advance

Paul