Not sure what the Maemo Bluetooth connector is; to pair my keyboard (Palm 3245WW), it goes something like:

1. Go to Control Panel -> Bluetooth -> Devices.
2. Hold pairing button on keyboard till light starts flashing.
3. Click New.
   <N800 searches, shows up keyboard>
4. Select keyboard and press OK.
5. Note passcode, or enter a different one (and remember it!).
6. Make sure trusted device is selected.
7. OK
8. Type passcode (from step 5) on keyboard, then Enter; careful here, as there's no backspacing, and no way to tell if you double a key.

If it didn't work, repeat; either you took too long, or typed wrong. I got it third try first time around; when I had to re-pair after OS2008 flash, I got it in one.