Step 0: May not be necessary, but if your device is password locked that can be aggravating, so i removed it using this guide: BB Password Removal
Step 1: (This caused me much grief to discover) Connect your blackberry to the target computer and be sure it fully connects using Blackberry Desktop Software. After that you close blackberry desktop software. This step tells the phone that the computer can be trusted, i presume. If you dont do this step 6 and 7 will fail, because when you try to communicate with the modem it locks up and device manager shows it with an error until you restart the phone and reset usb settings.
Step 2: Activate the Engineering Screen. Turn on the phone and go to the home screen. Hold down Alt+Left Shift and while holding them down press H. This will bring up another screen with various information listed.
Step 3: Go to : BB Code Generator. Click BB Escreen Keygen, and enter the Device Pin, App Version, and Uptime listed on the screen of the phone, and press Generate.
Step 4: You will be provided with a Key at the top of the screen. Go to your phone, while still on the same screen as the listed information, type in this key. You will not see what you are typing, but it is listening. Use all lowercase letters and the alt key for numbers. After you have done this the sceen will change. You have unlocked the real Engineering Screen Contents.
Step 5: Select Radio Engineering Screens (should be the first option), then to Test Commands for Lab Use. Then go to Falcon USB to PCAP, and set it to True. Return one screen and go to USB Mux and Enable iADTE/iFTA/Hypert USB. If all the drivers are correctly installed, this will expose the iDen modem.
Step 6: Open up Iden Lab RSS 25, and go to Tools>Options. Set your default software path to the Iden Lab folder (wherever you extracted it), and check the USB Port option. Click Test. If you get a Success dialog, proceed to next step. If not, double check that you have the Motorola Iden drivers installed, and that you have connected the device with BB Desktop Software on that computer at least once. Also be sure you have closed BB Desktop Manager.
Step 7: In Iden Lab RSS 25, go to File>Read Phone. It should read the phone and you now have access to the code plug. When you edit the desired values, go to File>Write Phone.
I used this for IMEI repair, however as the subsidy lock parameters are there, this could could the way to unlock the device as well for whatever purpose or intent you might have.
I was able to do this on a Windows 8.1 computer. I did have some trouble with a Windows 7 PC because Iden Lab RSS seems to prefer COM Ports 1-8 or 1-9. Windows 7 assigned the Iden Modem to port 21. I had to go into device manager, find the modem, and manually change the com port to 1 or 2 before it would even try to connect to the device.