the videos will illustrate better ... but I'll try
The 4" and 3.5" RIA guns (and Citadel) have a full length guide rod that goes through a special reverse plug under the barrel. If you lock back the slide, you can see a small hole drilled through the rod top-to-bottom.
You insert your bent wire/paperclip/whatever into that hole, and let the slide go forward until it runs into the wire, and now the slide isn't under spring tension.
You can now easily line up the takedown notch and slide latch lever, pop out the assembly pin and have the slide off.
Once you have the slide off, the entire recoil assembly comes out as a unit, pinned together by your little paperclip/wire. As nothing in there needs to be spotless shiny clean, you can just spray it out with CLP or a dry-lube.
Pop the recoil assembly back in after the whole gun is clean, make sure the reverse plug's ears are lined up right, and stick the slide back on the frame. Nothing is under spring tension, so you can easily re-pin the barrel link with the assembly pin and get it into the gun without fighting the recoil spring.
Now lock the slide open again, and remove your little home-made tool, toss it in your gun cleaning kit to become lost and never seen again (mostly joking, I made some nice ones out of coper jewelry wire that don't get lost)