The SIS745 chipset provides the "USB Open Host Controller Interface".
The Open Host Controller Interface is a standard by Compaq/Microsoft/National for accessing the USB PC hardware (also called USB host controller).
For more information, see : http://h18000.www1.hp.com/productinfo/development/openhci.html.
Linux provides the usb-ohci driver to access the USB host controler.
As root, load the module :
[root@localhost /root]# modprobe usb-ohci
If it doesn't work, you have to configure your kernel for it.
In the kernel configuration menu (# make xconfig).
Say Y to "Support for USB".
Say Y or M to "OHCI (Compaq, iMacs, OPTi, SiS, Ali, ...) support".
And compile this new version of your kernel.
For more informations about using the USB under Linux, see : http://www.linux-usb.org