Yay! First hack!

How-to:

* download and install CSR BlueSuite

* connect Flip4 with micro-usb

* press and hold Vol.Down + Play for 12 seconds or so. Flip4 detects as a usb device.

* launch PSTool.exe

* in popup, select USB, OK.

If no message pops up, you're in!

* In main menu, File->Dump, save current config to a file. This is a backup for a case you change something and can't change it back.

* in Filter box, type "local", and pick an entry that says something like  "local user-friendly name".

The value should read "JBL Flip 4".

* change value to your liking, click Set.

done. Now, disconnect usb, and … I don't know how to wake it up, the advertised combo Vol.Up + Vol.Down + Play didn't help. I had to unplug the battery.

UPDATE: hold power button for 14 seconds, it switches off. Then powers up as usual.