I have a Scientific Atlanta 3250HD cable box. I want to be able to change the channels on the box by sending commands from a computer.

There is a USB port on the front of the box - when I plug a USB keyboard into that port, I am able to change the channel by keying the channel number in on the keypad.

I'm wondering if its possible to send the keyboard commands from a computer? I doubt I can use a straight USB to USB connection, since both devices are host controllers...

But what about a USB to serial to USB connection?
Has anyone else managed to get something like this working?

The USB port is mostly useless. I'm sure you could use it but there isn't much use for it. You can also use Firewire.

Why not use IR? I've been using a USB-UIRT for 3+ years now to control my Moto box from a PC.