1 ) Go here to this post in this thread ( Baseband results anyone? Bueller?
) and get Gearhead's baseband zip file. Note his discliamers, the credits he gives, and his instructions. I strongly suggest while you're there in that thread, take the time to read about this file, about baseband and what it does.
2 ) As Gearhead says, rename the file update.zip and put it in your SD card's root directory. If you downloaded the file directly onto your Droid, use a file manager or terminal emulator to do this. If you downloaded the file into a computer, connect the Droid to the USB on that computer and transfer the update.zip file to the SD card's root directory. Make sure the file name is update.zip (not update.zip.zip as Windows may try to name it).
3 ) Turn off your Droid, then hold the hardware keyboard X key down as you turn it back on. This reboots your phone into Android System Recovery (aka SPRecovery, Nandroid, etc.).
4 ) Read Android System Recovery's instructions (in red). Use the volume control to move between menu items, the camera button to select them, and the power button to back out of a menu. With that, select the "install" menu option.
5 ) Move to the "Allow update.zip Installation" option and select it. It won't show any action, but it will allow you to do the next step.
6 ) Move to the "Install /sdcard/update.zip (depreciated)" option and select it.
7 ) At this point Android System Recovery will install the new baseband. As Gearhead mentions, the status bar won't update completely, but when the process says it is done, it is done.
8 ) Use the power button to get back out to the "reboot system now" menu item and press the camera button to select that option and reboot.