Pb Installing Bewan ADSL USB on FC1

I have an "BeWAN ADSL USB st" modem fully functioning on the network in
another not Linux box.
I have got today the last Linux driver from http://www.bewan.fr/ (no
direct support as of today): version 0.8.0, 2004-02-02 for kernels >=
2.4.10.
I have made it. But some pieces are missing; for what I understood, may
be limited to the ppoatm plugin to the pppd. See attachment.
How to manage it ? I was a UNIX guy for 10 years.

#!/bin/sh

# Source function library.
. /etc/rc.d/init.d/functions

# set to correct product (USB or PCI)
UNICORN="unicorn_pci_atm"
#UNICORN="unicorn_usb_atm"

# default VPI, VCI and encapsulation
VPI=8
VCI=35

# ANSI=1,G.lite=2,MULTI=3,G.dmt=4,
MODULATION=1

# pppd version 2.4.0b2 patched
#PPPD="/usr/src/ppp-2.4.0b2/pppd/pppd"
#PLUGIN="/usr/lib/pppd/plugins/pppoatm.so"

# pppd version 2.4.1
PPPD="/usr/sbin/pppd"
PLUGIN="/usr/lib/pppd/2.4.1/pppoatm.so"

RETVAL=0

stop() {
    killproc $PPPD >/dev/null 2>&1
    /sbin/modprobe -r $UNICORN >/dev/null 2>&1
}

start() {
    /sbin/modprobe pppoatm
    [ ! "$?" = 0 ] && return $?
    /sbin/modprobe $UNICORN ActivationMode=$MODULATION >/dev/null 2>&1
    [ ! "$?" = 0 ] && return $?
    sleep 10
    $PPPD plugin $PLUGIN $VPI.$VCI
    [ ! "$?" = 0 ] && return $?
    return 0
}

echo -n "$1 $UNICORN $PROTOCOL $VPI.$VCI $ENCAPS"

case "$1" in
    stop)
	stop
	;;
    
    start)
	start
	;;	
    
    restart)
	stop
	start
	;;
    
    *)
	echo $"Usage: $0 {start|stop|restart}"
	exit 1
esac

RETVAL=$?
if [ $RETVAL = 0 ]; then
    echo_success
else 
    echo_failure
fi
echo
exit $RETVAL