Do you mean you have been researching how to recompile it WITH
USB support? I have a USB mass storage device and I had to recompile a new kernel to gain support for it. I had to enable ISD-200 support and scsi disk support when I did 'make menuconfig'. I don't believe the default kernel that comes with RH7.3 will have USB support enabled, so you have to recompile a new kernel and make sure the option is enabled.
Instructions on recompiling can be found