It's impossible for us to have configuration options for every type of setting, but you should be able to use a style sheet to position the module how you want. If you have questions, let us know, but you can start with the Moduleclass Suffix in the module, which will give the Invite module a unique class (moduletable-jfbcinvite, for example), and then you can use a margin to position the module how you want.
Unfortunately, the module works by creating an iFrame to Facebook, and so we have little control over how the contents of the Invite module looks.
Finally, I just registered on your site, and could not access the page you linked to above. Just wanted to let you know.
Thanks!