Thank-you for contacting Slingbox Forum. I understand the need for use of the Slingbox with your MAC.
You are now able to view the Slingbox on Watch at setup.slingbox.com on Mountain Lion OS10.8. The information in the following link will confirm this:
You may need to update the Slingbox or maybe the software on the computer designed to run the Slingbox program.
Keep us posted!
Have a great day!
Sling Moderation Team