USB booting :: DSL USB install for dummies?

Sorry to bother but just another repeat question. I want to run scanModem tool. I have downloaded it and saved in my USB drive via XP. However when I boot in DSL from live CD, I don,t know whether it is recognizing my HD and USB or not? I don,t know how to mount USB and which command I should use to run it from USB drive( the instructions on website are only about running it from HD and floppy drive. I don,t have floppy drive on my laptop and also don,t want to use my HD. So what command should I use. And what command should I use to save the result of scanModem back to my USB key( not HD).
I will be thankful for help.

original here.