Hello Marco,
I am not sure if you mean that you have purchased both the tone filter and the 'Q' switch. Either way, what you seem to be after is what we call 'east meets west' custom electronics, so named after the first bass we put them on. You can see that bass here:
http://www.alembic.com/info/fc_emw.html We are closed until Tuesday because of the 4th of July holiday here in the US, but I'll ask Mica what she suggests. I do not know if you have everything you need to make that modification. We have not made many instruments with those electronics, so far.
On another note, congratulation on your bass, which I have actually played, since I know you bought it from a friend of mine. I saw him at my old store where he teaches guitar, and he asked me what the best way to sell his Alembic would be; so I told him to post here first before trying e-bay and...well, you know the rest. I am glad it found a good home.
Valentino
