I've dyed a whole bunch of stuff. Once I dyed a pair of canvas chucks black. Worked out nicely enough. The rubber parts got a bit colored too but I didn't mind. I used one of those machine wash dyes. Dunno how the suede would react to machine washing though. 🤔 Might not like it. Mind you, you can pretty much only dye natural fabrics, so if the tongue isn't cotton, dyeing is most likely not gonna work.