(Theoritical mind you, just thoughts, I'm a righty.)
I wanted to modify my AV8R to choke it up a little bit like a ball bat for easier top hat access. I posted here for ideas.
One good idea was to remodel the stick using "Sculpey" firing clay. $2 per 2.25" x 1.75" x .75" block of what looks like fudge cakes, various colors. Take it out of its wrapper, mold it how you wish, get more to build it up. Then use thin knife to separate, maybe in modules and in kitchen oven at 275 degrees F. for 15 minutes per .250" thickness (allow more time if thicker, not hotter). Lightens up as moisture evaporates it. To my local craft store (A.C Moore) is where I got it. They sell for $10 (same mfg.) an oven temp thermometer as ovens vary to accuracy. Store recommended an adhesive called E6000 for ceramic to plastic bond, though permament, about $4.
Maybe you can remodel your X52 to your grip?
I bet Yahoo! Groups has a forum about modifying joysticks or Google it. You can't be the only guy with this problem.
Another idea I like I got here, I played with thinking it out is plumbing pipe insulation foam, 8 feet for a couple dollars. You can cut it and layer it like the clay. I used double sided carpet tape to adhere it.