I had to strip down mine (although non-G version). As Dan Daniel stated above, you have to remove the lens shroud (along with leatherette which is veeeery flimsy) before reaching the shutter button. Then, the rest can be done. The button itself has a cut-out, in which the shutter lever sits. You can add something to that lever in order to make the camera fire earlier. If you are good with tinkering, it's an easy task. This is a very good resource, which covers Copal MXV shutter, but you can use it to see what you will be facing:
http://ratfactor.com/yashica/
Of course you need to go only as far as "Remove the top cover" section goes, the rest involves disassembly of lenses and shutter.
P.S. Is this Huss Hardan from comments section at Casualphotophile?