How can I use a greater USB charge current without device enumeration?
You can put a charge detector in parallel as long as you keep the stubs extremely short. I have done this before with a Fairchild charge detector. Don't remember the exact part number off the top of my head.

Or you could take a look at the BQ24392 from TI. It does its own enumeration (well, not enumeration... it does the charger detection upon initial connection, then connects the USB bus to the host), but it passes the detection results out, and it incorporates a USB bus switch so that the USB traces pass through it to the host. No stubs. It is specifically designed with USB 2.0 in mind. It correctly detects every type of charger in the known world, whether the charger is compliant with USB specifications or not.

But there may be a simpler option. How big is your battery? For smaller batteries (say less than 1 Ah) it may be easiest to simply always enable the 500 mA of current draw from USB. Of course, this means you will not comply strictly with the USB spec which dictates that until a profile is assigned, you have to stay under 100 mA. But in practice, it will work OK. It is rare, nowadays, to find a host which will object to the 500 mA being pulled from the USB port.