First thing, make sure that Self Service is appropriately setup in Settings -> Computer Management Framework Settings -> Self Service. Once you've done that you just need to create a new policy with whatever installer package you want to install with the Triggered By option set to "None (or Self Service Only)" and set the options you want in the Self Service tab. Then you should have a new policy available for install in Self Service. By the way, these steps are for 8.73 and not 9.x. We haven't made the leap to 9.x yet. Someone using 9.x can chime in on the steps for that version.
