Just to nip this in the bud before it gets started. The Z110/120BT runs completely different software then the previous X series. It will not run testmode and will not work with any software mods that are on this forum. There will be no hacks for this unit in the foreseeable future. If that ever changes it will be posted and stickied on this forum but likely will never happen.
MOD NOTE 11-24-2010: Recently a testmode file has materialized that does work on the 920/120BT units that will allow access to the file system of the unit. Unfortunately that is all this file does at this time. It does not offer a way to hack or mod any of the software in these units what so ever and there are no changes expected in the foreseeable future. If there are this thread will be updated. What that means is no UI hacks or mods, no software bypass, and no additional map or map upgrades are currently possible. Please do not apply the mentality that this will give you the same capabilities of the previous X and F series units.