I did some groupware integration for http://www.group-office.com/
But thats just for add email accounts, change pass, etc. in the groupware.
Well, should be possible that you find a section called Groupware where you can add users to it and it creates it on the groupware server, has to be a different one. Because its managing postfix, courier, cyrus, etc by itself.
So ispconfig and sogo would screw up because both try to manage the mail programs.