If your old Router is an ADSL Modem/Router you will be able to - just input the settings provided by Tiscali into the router admin page. If you are not sure post back with the make/model and we'll try to help.
If not, the answer is no. The USB modem will need the software to work, which you cannot install on the wireless router. You'll need to buy one of
these. I have this model router and it works flawlessly.
Good luck.
Andy