If you are reading that then you might find this useful:Finished Osprey book "French Foreign Legionairre vs Viet Minh Insurgent" by Martin Windrow---three good accounts of actions that would make good scenarios in ASL.
Devil's Guard, author George Robert Elford. Probably a work of fiction though:
I emailed it to Xavier (of LFT) and his comments on it were:
There has been no SS battalion in the French Foreign Legion as such. What's true, nonetheless, is that many Wehrmacht and SS soldiers joined the Legion after Germany's defeat, and plenty of them died in Indochina, true. But they were not used as an organic unit, which is completely logical.