I just changed mine on my P5C to 8# wolfs. You have to mildly compress the spring from the rear of the slide, turn the spring 90 degrees and pull it out through the side hole on the slide. You would think it pulls out from the front but it must pull from the back. You put the new ones in the same way from the back forward. Make sure to set the retainers in and feed the spring over them because you can't get the retainers in from the front once the springs are in. The spring and retainer are a tight fit and if you rotate the spring as you feed it it has a better chance of "screwing" on to the retainer. Hope this helps, good luck.
Try just rotating the spring onto the retainer without actually installing them into the slide to get the feel of it, rotate on and reverse rotation direction to get off. I kept fiddling with it 'till it finally worked. Emery cloth and lube were my other thoughts but it didn't have to come to that. Be patient !!
Good news! Brought out the ol' reliable hydraulic jackhammer and they're in. Unfortunately, I now need a new frame.
Did something different, ocseke. Instead of screwing them in the retainer (it was going the other way around), I first inserted the retainer, grabbed it tightly, pushed and at times forced the spring in. Did it by pushing the spring from the back, slowly but surely while keeping the retainer secure. Took fifteen minutes. Spring basically inserted itself. A little Rem oil helps.
Couldn't screw them in. My fingers would not help. But you sure gave me the idea on how to do it. And for that I'm grateful. Now the only thing I need is a new frame!