I doubt what you are trying to do will work... You are wanting to plug the USB dongle into the modem, and have the laptop connect to it wirelessly, am I correct?
I am going to say it won't work for 2 reasons.... First, (need a model number) but that modem likely only supports USB OR ethernet....
Secondly, I don't think that you would be able to use that USB Dongle for that purpose... it is to connect to a laptop or PC, and connect to a wireless gateway.
A third reason, is that unless that Modem supports NAT, you wouldn't be able to have both the PC & laptop on the internet at the same time (assuming the wireless USB dongle idea worked.)
On that same site you linked, you could probably find a wireless router for not too much more than the USB dongle, and it would also allow for future network expansion, should you get additional PC's, or if someone with a laptop visits.
