tbonesmith,
Think were in the same boat , am looking for the same info myself for the following Boer war bandoilers i recently bought on ebay, the top one is very hard and has cracks , the bottom one is realy nice.
The top one has been covered in something recently and smells like sun tan loation. want to remove whatever it is then begin to try and soften/clean etc.
looking on the net found this site,
The Reenactors Guide to Leather Care in the 19th Century
as I wanted to use old and tried methods as opposed to new stuff, after searching a few sites seems water, saddle soap, neat,s foot oil and animal oil (tallow) come out on top.