It turns out it’s pretty straight forward but your phone must be rooted for this to work and you must have enabled usb debugging.

The process goes something like this…

First on your phone navigate to Settings -> Applications -> Manage Applications -> Handcent SMS and click the Force Stop button to close handcent sms.

Next we retrieve the preferences file where the password is stored:-

$ adb pull /data/data/com.handcent.nextsms/shared_prefs/
com.handcent.nextsms_preferences.xml

Then edit the file you just pulled, find and remove the line that looks something like:-

<string name="hc_password">0cc175b9c0f1b6a831c399e269772661</string>

Next we push that file back to the device as follows:-

$ adb push com.handcent.nextsms_preferences.xml /data/data/
com.handcent.nextsms/shared_prefs/com.handcent.nextsms_preferences.xml

Now open handcent sms and the password should be removed ready for you to set another!

Obviously the above commands should be entered on one line, line breaks have been added to wrap the content…

The instructions are located in the extractrom.c file itself and reproduced here for clarity:-

 * REQUIREMENTS
 * This program requires a patched unshield 0.6 to correctly support newer
 * installshield cab files.
 *
 * $ wget http://bit.ly/aWIjG2 (used bit.ly link for blog due to styling issues)
 * $ tar xzf unshield-0.6.tar.gz
 * $ cd unshield-0.6
 * $ patch -p1 < ../unshield.patch
 * $ ./configure --prefix=/usr && make && sudo make install
 *
 * COMPILATION
 * $ gcc -Wall -lunshield -o extractrom extractrom.c
 *
 * USAGE
 * $ ./extractrom /path/to/RUU.exe
 *
 * If successful it will create rom.zip in your current directory.
 *

(pay some attention to the NOTES and TODO sections - at the moment the tool doesn't clean up its temporary directory...)

Example Usage:-

$ ./extractrom RUU_Bravo_O2_UK_1.20.207.1_Radio_32.36.00.28U_4.06.00.02_2_release_124865.exe
Extracting data1.cab...
Extracting data1.hdr...
Extracting rom.zip...
Done!
$ ls -lh rom.zip
-rw-r--r-- 1 kenny kenny 147M 2010-06-24 13:06 rom.zip

You can download it from here: extractrom-0.1.tgz.

Update (2011-12): This is now maintained in github at: https://github.com/kmdm/unruu/