In reply to abcdef:
I've tried few options on Scarpa SLs (Grangers Wax, Nikwax watery solution) and nothing worked perfectly if you don't apply it often enough. Just keep that in mind. Maybe it's the type of leather, though.
Whatever you end up using, just man up and get your hands dirty. I tried different cloths and nothing works better than your own hands. Yup, it's greasy and it takes a good effort to wash your hands after that, but at least applying the waterproofing material is somewhat easier. It allows you to get in the seams and narrow bits a lot easier.
I just got some Scarpa HS12 cream for my Nepal Extremes. The discolouration is awful, but hopefully that works. I found Berghaus Yetis to be adequate for the job as long as you don't damage the rubber (super easy for clumsy person like me). I usually keep a pair of Sealskins socks for emergency use as well.