Since I already had an rts2 mount and was too cheap to buy another mount, I sharpie marked the top surface of the mount then I screwed the dot gently to the mount and scribed around the base of the dot.  Then I took the scope off and used my cheap Chinese mill with the smallest end mill I own and cut up to the scribe lines.  With some patience(and a steady hand) you could do the same mod with a dremel and some needle files.  Having said that if I didn't have a mount already (and was impatient to