Also, with the pressure off, try spinning the axle a little each time. The clip has a gap in it (looks like this)
Having spent the better part of 8 hours trying every thing else I could think of, and having read somewhere that with the gap on the bottom, the top of the C clip would sink slightly, reducing contact with the inside surface that keeps it locked in, I thought I might be able to have a better shot at it if the gap would be at the down opposition. So, by spinning it you should have the least resistance to getting it out if the gap is directly at the 6 o'clock (bottom) position. (It's at the 12 o'clock position in the picture above.)
The clip itself is located on the very end of the assembly, about like this:
I spun it slightly, and jammed two large (18 inch or so) flat bladed screw drivers behind the CV joint at the same time, popping them towards the passenger side to kind of get the CV joint/axle assembly (I didn't take the CV joint apart, I was going to use them for the core charge.) to just let go.
After a few minutes of spinning and muscling, sitting on the ground with the front end jacked up in the air (on jack stands, of course: ALWAYS use jack stands) I "popped" the screw drivers in using a lot of muscle and that thing just let go and the CV joint came flying out.
And, I sincerely hope I never have to do it again.