They are all over the internet.
There should be some vids on youtube.
These are some of the better sites for it, but mostly cover the MKIII pistol.
The good news is that the .22/45 share a lot of the same parts. The bad news is that my .22/45 is still stock and I haven't shot it in a long time.
When you knock the upper off the gun, re insert the magazine.
Notice the magazine disconnect rubbing on the magazine.
What you need to do is remove the hammer pin. The hammer, MKIII hammer bushing, magazine disconnect, and magazine disconnect spring will come right out. You would want to remove the b the bushing from the hammer. The disconnect and spring would come off with it.
You will need a MKII bushing of some kind.. Now these can be purchased from several places. I got mine (Volquartsen MKII bushing) from www.rimfiresports.com
. Majestic Arms makes one call their 3.2 bushing, and Clark Custom guns makes what many consider the best.
You would install the MKII bushing back into the hammer, the hammer back into the gun, the hammer bushing pin back into the gun, and you would be done.