It depends on if your lipo shots are intramuscular shots (IM) or subcutaneous shots (SQ). I discussed the difference of injecting IM or SQ here
If subcutaneous you can inject anywhere you would do your hCG injection. If intramuscular you want to be sure to inject somewhere where you can go into the muscle- many people do the top or side of their upper thigh, or their deltoid area or buttocks (if you can reach!)
You can see my entire post on lipo shots here.