From what I've read the 770 can never go into discoverable mode. This is fine since my Krzr (Verizon K1M) can do it. For the verizon K1M you do the following:

Go to the "Settings & Tools" tab
Hit option 3 "Bluetooth"
Hit "Settings"
Hit option 2 "Discovery Mode"
Select on, then hit OK
The phone should be in discovery mode for the next 3 minutes.

To pair it with the 770, just add it on the 770. Your 770 should be able to "see" the Krzr. The k1m will prompt you for a code on your phone (its on the 770). Then it'll ask if you want to pair a few times. Just click ok or yes each time. Its fairly straightfwd.