From LQWiki

Here a brief installation guide for a pppoatm connection with an ADSL external modem (Trust 235a Speedlink Webmodem) on Mandrake 10.1 Community. First download the kernel-source(-2.6-2.6.8.1-24mdk.... for example) from `install software`(cd`s)or a new kernel from Kernel.org (I tried it with kernel 2.6.9) and unpack the kernel to /usr/src/. Once inside the directory run "menuconfig" as the user "root"

1) Go to the section Device Driver -> Networking Support -> Networking Options -> and select the following to be installed:

(M) Asynchronous Transfer Mode (ATM)
(M) Classical IP over ATM
(*) Do NOT send ICMP if no neighbour
(M) LAN Emulation (LANE) support
(M) Multi-Protocol Over ATM (MPOA) support
(M) RFC1483/2684 Bridged protocols
(*) Per-VC IP filter kludge

2) Then Go to the section Device Driver -> USB Support -> and select the following:

(M) Support for USB
(M) Alcatel Speedtouch USB Support

3) Save your changes and exit menuconfig. Now run "make", after that finishes then run "make modules_install", and then finally "make install". If your computer freezes restart your system. Then try again.

4) Next remove these packages from your system:

liblinuxatm1-2.4.1-4mdk
libusb0_1-4.0.1.8-2mdk(*)
ppp2.4.2-7mdk.pppoatm2.4.2-7mdk

5) Go to the Conexant USB ADSL Modem Linux Driver project and download:

ppp-2.4.1-6plf.i586.rpm
linux-atm-2.4.1-1.i386.rpm
libusb-0.1.6-3.i386.rpm
libusb-devel-0.1.6-3.i386.rpm

6) Now install them.

7) then download cxacru.tar.bz2update for new kernels(those are 2.6.x kernels the other cxacru files are for 2.4.x kernels)must(perhaps can) be unpacked in /usr/local/src. Run "make" in the terminal using the user "root".

8) Go to file /etc/cxacru open it and modify the next items:

PROTOCOL_MODE(standart=1)=2 ,VPI=8 VCI=48(this counts for the trust235a)and P_ADDRESS= NETMASK= GATEWAY= (yours)then go to file /etc/ppp open it go to file `options` (root) remove it and replace it with new options file(create)with : noipdefault
noauth
persist
lcp-max-configure 50
usepeerdns
name any
user "username"
defaultroute
plugin /usr/lib/pppd/2.4.1/pppoatm.so 8.48
(8.48 are the vpi/vci values of235a modem)than go to ~configure your computer~(perhaps it is better to do this before removing packages{ppp-2.4.2-7 etc}sometimes computer reinstal ppp-2.4.2-7 and the other files from linux version cd and you have to repeat step 4!) go to section Network and Internet -> Manage Internet and fill in user name, password, ip, and so on. Now restart your computer and thats it.

(*)when removing libusb0_1-4.0.1.8-2mdk there is a posibility that you also remove ~configure your computer~ but you should be able to reinstal it