This is the script I use on Mandrake 10.0 and Suse 9.2 with KDE.
It was written by Philmo from "L'alliance francophone" team.

#!/bin/sh
BOINC_EXE="nom_de_l'executable_boinc (name of the boinc_exe version)"
BOINC_DIR="/repertoire/d'installation/de/boinc
(/directory/where/boinc/is/installed)"
BOINC_PARAMS="-return_results_immediately"
echo "Démarrage de BOINC...(Start of BOINC)"
cd ${BOINC_DIR}
./${BOINC_EXE} ${BOINC_PARAMS}

You save it ("autoboinc", for exemple) and chmod +x this script (it must be
executable)
You put this script in home/your_account/.kde/autostart
And you set your options in KDE so as your account starts automatically when
you boot your computer.
And it works fine: I just push the "on" button of my machines and Boinc
crunches happily :o)
I have made the following change because I have several machines and want to
control boinc via boinc_manager:
BOINC_PARAMS="-allow_remote_gui_rpc"

My second script (more simple as I have written it myself):
boinc is in  home/your_account/BOINC
And you put the following script in home/your_account/.kde/autostart

#!/bin/sh
cd /home/your_account/BOINC ; ./boinc -allow_remote_gui_rpc

You save it and chmod +x this file (it must be executable)
And it works for me.
(please note that BOINC and boinc are different directories because bash is
treating capital letters and lower-case letters differently)

Regards,
Arnaud