Mine (a 2.25 diesel) was connected onto one of the supports of the battery holder / platform thingy. Basically just a hole drilled through the support and bolted on.
Mine is earthed to the engine block and the radiator support bracket - definitely not standard, but it works. As the engine sits on rubber mounts, it sort of makes sense to provide a good return from the starter motor via the block.
Mine is connected to the bottom of the battery tray, which in turn is connected to the chassis.
I believe this to be the norm.
Provided that it is a good clean secure connection you will br OK...