finally, someone who has answered from the void!! thanks!

ok, this is what i do.

0. open x-term and login as root. edit main.conf so that the disable plugins line says "DisablePlugins = " (i.e. i enable everything). then stop and start the bluetooth daemon with stop / start bluetoothd.
1. on stowaway - hit ctrl left-fn + right-fn to get the keyboard into pairing mode
2. on the N900, turn on BT and choose to add a new device. i also leave the N900 discoverable (though this isn't really necessary).
3. N900 searches and successfully discovers the keyboard.
4. selecting the keyboard, N900 displays a 4 digit pairing code.
5. i enter this on the stowaway using Fn + the digit keys. then i press ENTER
6. on N900 it shows device is paired.
7. i quit the bluetooth dialogs on the N900. i don't disable BT btw. it remains on all this while.

all this while, the n900's physical keyboard is opened.

back on the N900 desktop, the bluetooth icon shows the keyboard isn't connected. i hit a few keys on the n900 and then a few keys on the stowaway - no luck.

then i use bluemaemo to re-establish connection to the keyboard. the BT icon in the system area changes colour to indicate an active connection.

then i exit bluemaemo. after a few seconds, the BT icon in the system area changes colour to indicate the connection with the keyboard was lost.

i open x-term and type a few keys on the stowaway, the BT icon changes colour to indicate the keyboard is connected. but no keys register in x-term. i leave everything idle and after 2-3 seconds, the BT icon changes colour again to indicate no active connection.

i have the sixaxis package so my phone is configured to use the sixaxis controller. i am aware stops working when i change DisablePlugins = line to remove "input". but this is a small issue for me.

i am also running the CSSU updates but i don't believe they have changed anything in the bluetooth stack.