It wasn't hard to find details about how to jailbreak the Cliq XT. The process involves installing some drivers and software on the PC side, then running software on the phone itself. If you follow the instructions to the letter, the process is just about guaranteed to work. The biggest holdup was typing the necessary commands on the Cliq's on-screen keyboard.
One extremely important detail to keep in mind when jailbreaking a phone: You must remove any antivirus or system-protection software. Any jailbreaking attempts may be discovered by said software and disabled, which renders the whole operation moot. I had AVG's free antivirus package running on my 'Droid phone, and the first time I tried the jailbreaking process, it shot me down. After removing AVG and restarting the jailbreaking process from the top, it worked fine. (I was also pleased to know the phone wasn't bricked because the first jailbreaking attempt was halted -- the last problem I needed was to have the phone killed before I could do anything.)
Once you've broken open the phone, outward appearances should not be all that different -- except for the presence of a Superuser program (with a skull-and-crossbones icon) in the App Drawer. This program isn't used directly, but it's invoked by other programs that need permission to make modifications to the system not normally possible.
Another addition -- that, again, isn't immediately visible -- is a new bootloader. This lets you perform all sorts of low-level functions with the phone: wipe the user data, back up the currently installed version of Android, or install a modified version of Android. To be safe, I made a full backup of the phone's state and saved the data to my PC. This proved handy later when I wanted to roll back to the stock Android installation and make comparisons, or just revert the phone to baseline functionality.
Adding new firmware
The next step was to pick a modified ROM. There are more than a few places to track down modified phone ROMs, and in each such community, I was able to find a whole selection of ROMs with different alterations. At TheUnlockr.com, for instance, there's a Cliq XT ROM that uses Android 2.1 and Motorola's "Blur" interface (aka "Motoblur"). Since my Cliq came with Motorola's Motoblur version of Android, I thought I'd start there and see how it behaved.
Once I downloaded the ROM, I backed up the phone and installed it. The backup and installation are, as I noted above, done through the bootloader, so the process is semi-automatic. All you need to do is copy the ROM file (a Zip archive) into the root directory of the phone's SD card, fire up the bootloader, and select the appropriate menu option.
Getting into the bootloader on the Cliq isn't hard. You turn the phone off, then hold the power and camera buttons down at the same time. Up comes a text menu from which you can choose various options: flash the system with a downloaded ROM; back up or restore the system to a file; connect the memory card to a host via the USB port (handy if you want to dump a ROM file in without having to formally boot the phone); and perform a number of other low-level functions.
The entire process of upgrading the phone through the bootloader, including making a backup, didn't take more than 10 minutes. I rebooted and found myself looking at a version of Android that resembled the version I had on my other, brand-new Android phone. Mission accomplished.