I actually have this new feature request already logged under the ID SMACK-37 (http://www.jivesoftware.com/issues). Currently, you’'d do something like the following:
This works with most current clients. However, according to the MUC JEP (http://www.jabber.org/jeps/jep-0045.html), this protocol should be phazed out over time so that official MUC invites can be used (see the JEP for more info).
So, I’‘m not sure what the official Smack solution will be. Likely, we’'ll implement the full MUC protocol all at once and include invites as a feature.