Nokia 770 bluetooth driver supports the HID type bluetooth keyboards, but not SPP drivers.

The Bluetooth driver can be downloaded here:
Source code is here:

hid drivers are in kernel so you cannot remove those without recompiling kernel and configuring them as modules. as for bt plugin, it is just wrapper around hidd daemon. run hidd --help to see more. then look at the btkbd script and write something similar with hidd instead of kbdd.

kbdd is userspace driver for serial keyboards and for bluetooth keyboards that support serial port bluetooth profile instead of more recent HID profile. This version supports N770 screen unblanking on key press (needed for IT2005 only) and also three additional bluetooth keyboards:

Possible Bluetooth Keyboards thread

Official Linux Bluetooth protocol stack

Serial Port Profile (SPP)
SPP defines how to set-up virtual serial ports and connect two Bluetooth enabled devices. SPP is based on the ETSI TS07.10 specification and uses the RFCOMM protocol to provide serial-port emulation. SPP provides a wireless replacement for existing RS-232 based serial communications applications and control signals. SPP provides the basis for the DUN, FAX, HSP and LAN profiles. This profile supports a data rate of up to 128 kbit/sec. SPP is dependent on GAP.

Which Bluetooth profiles are supported in Nokia 770 Internet Tablet?
Nokia 770 Internet Tablet complies with Bluetooth 1.2 specification. SAP (SIM access), FTP (File Transfer), DUN (Dial –up Networking), GAP (Generic Access) and SPP (Serial Port) profiles are supported.

Think Outside Stowaway Universal Bluetooth Keyboard

Freedom Mini Bluetooth Keyboard