Yeah, its a PITA. I use one similar to this one. It only has one wire and fits with gentle pressure. To make it easier for me I bent the tip of the brush like an "L". To clean the thin spoke crack I grab the brush with my right hand and push the tip of the "L" into the wheel with my left hand. You can find it in Autozone, etc. For the inside of the wheel I use a Daytona brush. Hope this helps.
Akrapovic Evolution with Carbon Fiber tips | ESS Akra Evo tune V2 | Dinan Pulley | iND Cosmetic Package (Color Matched Front Grilles/Reflectors/Side Gills) in Space Gray | LUX H8 Angel Eyes