Dude, sorry to hear of your woes. But, the job may not be as difficult as you might think. Installing that clip ring in the CV outer race shouldn't mean disassembling the whole thing again. You should be able to move the boot out of the way & slip the opening of the clip ring around the shaft to get it in place.

I highly recommend that you get some anti-sieze to put on the shafts of any knuckles or ball joints that you take apart. It'll save you many headaches in the future. Basically Isuzu (or whoever they get them from) designed them with too shallow of a taper and when you tighten the castle nut, the shaft siezes in place (I know this first hand from a project I worked on at work years ago).

When you go to do the other side: Remove the castle nut, put the castle nut back on upside down to where it is flush with the surface you will be pressing on, then use the puller. The castle nut should protect the threads (as well as the hole for the cotter pin).