These hacks are out of date, for the EICON modem, please use the ECI Driver which includes all the EICON patches listed here.
For PPPoE with an Alcatel speedtouch USB modem, please use Speedtouch Driver.
Here you'll find hacks of the French ECI modem driver.
And another hack of the Speedtouch USB driver to support PPPoE.
- a test version of the driver for the Eicon modem
- two patches to enable the ECI driver to support PPPoE with rp-pppoe, as some providers don't seem to support PPPoA. these patches are against the 0.5 driver and the CVS driver
They enable the use of pppoe with the help of a virtual ethernet interface called tap0, to use these, you should make sure you have:
to install: you should patch your ECI driver sources with the right patch: 0.5 or CVS at your option with a set of command like these:
cd /where/your/driver/sources/are
patch -p1 < /where/you/have/downloaded/the/diff-llc-snap-patch
make install
Next you'll have to: modprobe the tun/tap driver
modprobe tun
Then launch the eci-load1 and eci-load2 manually. (please refer to the startmodem script to know what parameters to pass to these programs).
And launch the modified pppoeci which will listen on tap0 for pppoe frames. eg:
/usr/local/bin/pppoeci -v 1 -vpi 8 -vci 35 -vendor 0x0915 -product 0x8000
Note that the modified pppoeci will remain in the foreground. (this is test only)
Then you can start to configure your rp-pppoe package and when it'll prompt for the ethernet device where the modem is connected, you should specify: tap0

I'm not responsible if it fries your modem. This works for me.
I usually hang out on #ECI on theOpenprojects Irc Network with a nick flysomething.
Please report success or failure here along with the output of lsmod, dmesg and startmodem if you want.
sample output with an Eicon diva adsl usb modem:
ppp0      Link encap:Point-to-Point Protocol
          inet addr:  P-t-P:  Mask:
          RX packets:20635 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20689 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:3223105 (3.0 MiB)  TX bytes:1291719 (1.2 MiB)

tap0      Link encap:Ethernet  HWaddr 00:FF:FC:21:80:E3
          inet6 addr: fe80::2ff:fcff:fe21:80e3/10 Scope:Link
          RX packets:22252 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22335 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:3774188 (3.5 MiB)  TX bytes:1796790 (1.7 MiB)

root     12703  0.0  0.2  2020  176 tty7     S    Jun29   0:00 sh /root/testpppoeci
root     12704  4.8  0.6  3740  428 tty7     S<   Jun29  64:50 /usr/src/test/usermode/pppoeci -v 1 -vpi 8 -vci 35 -vendor 0x0915 -product 0xac82
root     12706  0.0  0.6  3740  428 tty7     S<   Jun29   0:00 /usr/src/test/usermode/pppoeci -v 1 -vpi 8 -vci 35 -vendor 0x0915 -product 0xac82
root     12707  0.0  0.6  3740  428 tty7     S<   Jun29   0:06 /usr/src/test/usermode/pppoeci -v 1 -vpi 8 -vci 35 -vendor 0x0915 -product 0xac82
root     12709  0.0  0.9  2024  616 ?        S    Jun29   0:00 /usr/sbin/pppd call dsl-provider
root     12710  0.0  0.6  1276  420 ?        S    Jun29   0:21 /usr/sbin/pppoe -I tap0 -T 80 -m 1452

About DSL
Auto-Configuration for the Connection between the DSL Broadband Network Termination (B-NT) and the Network using ATM
Protocol Independent Object Model for ADSL EMS-NMS Interface
Protocol Directory - ATM Encapsulation Methods
rfc2364 - PPP Over AAL5
rfc 1483 - Multiprotocol Encapsulation over ATM Adaptation Layer 5