You had better google the heck out of this and check your model number over and over before you do this. As I said before, this is not recommended unless you know what you're doing.
If you're absolutely sure about this, go here for the Belkin F5D5231-4 firmware v1.10.008 update. Don't come crying to me if this kills your router or burns you house down.
Good luck.
Jeff Borders
revised 07/09/04