I've never done it, but some swear by it. They grind down their favorite rub to a fine powder and add it to some de-fizzed coke and inject away.
Jambo Pit - UDS - Lang 60 (Sold)
18.5" & 22.5" Weber Kettles - Smokey Joe and Mini-WSM - Bubba Keg - #2 La Caja China
Impeccably Accurate BLACK & RED Thermapens
Operation BBQ Relief Founding Member
I am Obsessive Compulsive about BBQ. Google it.