From what I found on the net, it doesn't seem like this modem requires any special drivers so it should be working. Check if you can see it listed when you run the command 'lsusb' on the command-line. If it's listed - go to the mint control center and try to configure your dial up settings (I don't have Mint installed at the moment but the GUI is simple enough to figure out by playing with it).
If you still need help - be specific on what you tried and what still doesn't work. We'll need to know what hardware you have and what type of internet connection you have