Sounds to me like you are going to use the permenant wiring as temporary wiring while you are working on the rest of your garage. I've done it on commercial jobs many times. Heck....I've "temporaried in" a panel before by "back feeding" a breaker with an extension cord. I wouldn't suggest doing it unless you know what you are doing, but I wouldn't have a problem with what you are suggesting above. The only problem is...I'm not an inspector.
All present, and accounted for, standing by for inspection, Sir,
The Watt Doctor