I have the manual for the capsule itself but it has nothing about the base in it (and I dont know if we ever had a manual for that!). We have just installed the base in to our car a couple of days ago and it has a few stickers on it showing installation instructions (maybe theyve come off your one though?).
There is two ways to install it - one for cars with the isofix system and one for cars without.
Our is without and basically all you need to do it unlock the stand underneath and extend that down to the floor. Then thread the belt through the bit that says 'belt here' or similar - you need to buckle the seatbelt and thread both straps through underneath bit.
I hope that made sense, if not let me know and I can take a photo of ours all installed and email it to you. If you need the isofix instructions I can write those out for you when I get a chance
Hope that helps