I use the Belkin F5D5050 on a Hughes HDVR2 Directivo that was originally hacked years ago with Sleeper's 2-kernal monte technique. 

Everything worked great for years, but this past December I decided to upgrade to Tivo 6.2 so I wiped my drives clean, Instantcaked with version 6.2, then ran PTVnet with USB2 turned off (since I intended to continue using the Belkin F5D5050).  

Everything I had read in the forums back in December 2006 made it seem as if this should work just fine; however, as many people on the forum have apparently found out, plugging in the Belkin to my usb port did nothing.  No power light, no connection light, just as if the usb port was not turned on whatsoever.  

It turns out that this is indeed the case, the PTVnet script fails to initialize the usb port if you choose to turn off USB2.  After a bunch of dicking-around, I discovered this work-around:

1) Get a serial cable so that you can access a bash prompt on your Tivo

2) cd to the "init" directory

3) edit the 011_usb.init file (I used the vi editor: "vi 011_usb.init")  by adding the following 3 lines within the if [ ...USB20_OFF] after line 20, which reads "rm -rf /lib/modules/usbnet.o" (make sure the lines are before the line with "fi")

     /sbin/insmod/ /lib/modules/usbcore.o

     /sbin/insmod/ /lib/modules/usb-ohci.o

     /sbin/insmod/ /lib/modules/pegasus.o 

4) save and exit the file

5) restart your tivo and watch in amazement as the usb port is initialized and your Belkin adapter springs to life! 

I've now got my Tivoweb and tyserver running again with v6.2, yippee! 

Hope this helps...