It's simple... and explained on the first page of this FAQ.
-EDIT- dang... didn't realize his pics are down... hang on...
Here's my version with new pics... Took a lot longer to edit and upload pics than anything.
Step one - Remove the two screws from left side grip panel (or remove grips completely).
Step two - Loosen asa / drop forward. If you're using the stock evil ASA / rail, you may have to remove the ASA to loosen the rail.
Step three - Remove the four screws from the left side panel.
Step four - Replace battery. Then reverse the above to reassemble marker.
Hope that helps.
-Howard