Thanks my friend.
Exactly the solution I have been looking for .
I have got it installed from the above web link
(abbreviated link) http://tinyurl.com/maemo262
via application manager open / upgrade
and Settings > fields no more grayed out
immediately connected my bluetooth gps

Establishing GPS fix not working as I am in concrete building,
but 10 satellites in view; in use: 0

Thanks again for your excellent solution and let me share it with
other users of Nokia 770

It took me 2 weeks to approach you directly.

==
follow-up

the only known problem is
bluetooth GPS is getting connected to Nokia 770 much faster
than mm's
Searching for GPS receiver - script
so GPS already connected (blue icon at top)
and mm is running
Searching for GPS receiver
over and over again

So new patched mm 2.6.2 looks to be not running
rfcomm to get info on already connected gps

Finally mm generates the following error message

Error connecting to GPS receiver
Retry ?
OK Cancel

(but gps is already connected and keeps connected)

Selecting OK doesn't work

I select Cancel
than select
Disconnect GPS name
from bluetooth icon on a top
than set gps off
as selecting
Disconnect GPS name doesn't work
and gps is always not but not visible to mm

I can run CLI
rfcomm
to get info that rfcomm0 device
rfcomm0: 00:12:01:01:00:94:99 -> MAC address of my bluetooth gps

It looks like the first MAC address is hardcoded
(no any idea why do I get MAC redirection)