Is it the silver (rev4) modem?
Either way, dont worry about the speedtouchconf script. There's a speedtouch package on the Mandrake cds, and also install pppoatm and its stated dependancies. Then put the microcode from your ISP's cd in /usr/share/speedtouch and configure /etc/speedtouch.conf. Lastly you need to put your username and password in the /etc/ppp/pap and chat -secrets files, and check your /etc/ppp/peers/adsl has the right info.
See my success
here and feel free to ask any questions if you need more details info after reading those linked threads.