I looked into that, but I think suExec is already running on my system as if I do a top, I see the apache spawned processes owned by the correct users.

As far as I can tell, the problem is the parent process, not so much the ownership. if the cgred daemon were reliable this wouldn't be an issue, but its not according to its own documentation. :(

If suExec doesn't do what you need, there's also CGIwrap. CGIwrap also works on other webservers as it's a CGI itself.