Reconditioned the seat belt webbing over the last week (scrub brush and warm soap and water... Then a little spray paint) and started breaking down the seat belt buckles today. I couldn't find any diffinative info on getting these apart so I carefully made my own way. I'll get some more pics as I go along but below are a few.
Take lots of pictures
Hold buckle with latch slot opening toward you and lever side of buckle facing up.
At this point, the splined pivot pin that needs to be removed is on the right side.
Give the base of the pin a small shot of WD-40
Push pin from other side of buckle to expose enough of a lip on the underside of the 'pry' side. Note the slot in the pivot. This is where the spring end sits. Next protect the finish as best you can (I used cardboard) and carefully pry a thin screwdriver, or mini finish-nail pry bar, under the splined pin and pry it upwards. Take your time, don't try to get it out all at once. Don't lose it when it pops out!
Once the pin comes out, take the rest of the pieces of the one buckle apart and try to get it all back together again so you know how that will go before you start taking them all apart.
Getting it back together was a little tricky until I found the key to getting the spring loaded correctly. I'll describe that later.