Under the config wizard for mandrake, it should have an option for alcatel configuration (presuming that it is an alcatel speedtouch usb model - I had the old turquoise cowpat one, but understand that the maroon mouse shape one - the speedtouch 330?? - should work as well).
Erm, also, when I was still using mine, I could often get it configured, use it and when I booted back and forth, it wouldn't play under mandrake - this turned out to be to do with firewalls, "shorewall" specifically. I ended up turning it off, and that cured the problem.
I have also seen various threads that have said, that it doesn't like it if you are trying to start it and stop it, using the graphic facilities (I did OK with the network facility though), these other threads mention using command "Start ADSL" or "Stop ADSL" - though you'd have to mess around with upper and lower case, as I can't remember - also, if you do a search for speedtouch or alcatel usb or adsl modems here at LQ, you should get quite a few threads that may be of some assistance, and guide you in the right direction.
p.s. I now use a SAR110
because I used to get rather pissed off waiting for the modem to initialise and disconnect between OS's - and if you do the search you should find a thread that mentions the snag with the "speedtouch.sh" file - I never did find a solution to that.