Lenovo ThinkPad SL Series hotkeys (brightness, volume and ultranav)

The company I work for gave to me a Lenovo ThinkPad SL500 notebook in which I’ve installed Ubuntu Intrepid (8.10).
Almost all has gone at the first shot but I discovered that the SL series is not a “real” ThinkPad and the thinkpad_acpi module doesn’t work at all with sl series laptops.
Volume Up, Volume Down and Mute buttons did not work and brightness was a mess: on power saving the brightness increased, pressing the brightness Up button (Fn+Home) decreased and pressing the brightness down button (Fn+End) increased.
Googleing at firs led nothing until…. I found an experimental module developed by Alexandre Rostovtsev (tetronimo).
Here a step by step guide to let Lenovo SL Series laptop hotkeys start working.