if they look like junk and you cant save them by trying, they are still junk, right?
Sometimes all you end up with is a fairly decent looker, good for display, but no weight bearing, and that can still be OK on a vintage bike or a wall, etc.; hey, they are bikin' history and pretty cool.
So, DO NOT oil up right away, but start by soaking, at least overnight, in warm to the touch, not hot, water. A little glycerin from the corner drug store mixed in might help too (they have been soaking wet before), then saddle soap the surface clean.
Dont punch any extra holes, but try to 'train' the sideflaps to turn back down. If they crack through the leather is dry rotted to no good, so dont try this dry! Being saturated they should bend down, and wont stay, so pad them with some clean cloths and tie wrap or tape around to the form you want and set to dry. DO NOT use any heat source to dry! A fan running ambient air over and through is OK to use.
There is nothing wrong with letting the saddle sit thus for several days.
Once dry the form should hold when you unwrap. If it does not, soak again and redo the forming.
If there is any color staining to do, do so now, before beginning the oiling process. Say, if you have light spots on a black saddle, use leather stain only on the light areas, then lightly buff to blend, repeat if needed.
When the form will hold you may start re-oiling. NEVER use motor oil; I recommend only Pure Neatsfoot Oil (Pure, not the 'Compound'), Set the saddle in the sun, or use a hair drier set on low only, and get warm to the touch. What you are doing is opening the pores of the leather to absorb better. Rub in a bit by hand, all over the surface, both top and the underside. I like to do a couple of good coats the first day, then hang to soak in. The next day I will do another, and likewise the next. At this point you need to determine if you should stop. It should look and feel much better, but too much oil will make a 'hammock' style (a Brooks, Ideale, etc.) too soft and sag. These type are also prone to tearing dry rotted leather, too far gone, out at the rivets. A pan-base leather topped saddle can still be usable when a hammock style wont be.
If/when you decide to stop oiling, rub in some Pecard's Leather Dressing (used by some museum curators for artifacts). It wont completely soak in, but will remain gooey to tacky, so buff it out after a week before sitting your new jeans upon.
Thereafter, when the suface begins to look a bit 'starved', rub some more Pecard's in.
IF you have doubts about the weight bearing ability of the leather after all this intimate handling, listen to that little voice, and dont sit on it (it will likely let go and you will hate yourself).
FWIW, Ive messed about with leather saddles for over 35yrs. and had over 100,000 miles on a 25yr. old motorcycle saddle when I gave it away, and it is still going. This is 'my way', and I know others have their way, but this has worked well for me.