You can control most anything in Indigo with an AppleScript. These are very simple scripts and look like:
tell application "Indigo"
turn off "Driveway"
execute group "ImHome"
For a full list of all of the commands available see the AppleScript section of Indigo’s Help.
Now for SmartThings to trigger such a script via HAM Bridge, the SmartApp must send an HTTP GET to your Mac. Details for that can be found HERE. Then it is simply a matter of creating a new command in HAM Bridge, and entering the AppleScript you want it to execute.
BTW, you can control SmartThings from a Mac, using HAM Bridge, or any app capable of making an HTTP request (browser, terminal, AppleScript, etc.). All you need to do is create an endpoint for the SmartThings you want to control.