Okay, since I haven't found a definitive guide or howto on this forum for how to install javaloader (unless I searched and actually looked through the threads), I figued that I'd make a simple HOWTO for it.
Mark (or anyone else), if you'd like to add to this, by all means...
1 - Download and install BlackBerry Java Development Environment (JDE) v4.0 from: http://www.blackberry.com/developers...de/index.shtml
2 - For ease of use, I am going to suggest using this step and adding the /bin path to your OS environment variables. In Windows 2000, XP, or 2003, you can right-click on My Computer and click on Properties (alternatively, Control Panel then double-click on System). Click on the Advanced tab. Click on the Environment Variables button. Under System variables, find Path and click on the Edit button. At the very end of this field, add a semicolon behind whatever is there (unless there already is a semicolon) and add C:\Program Files\Research In Motion\BlackBerry JDE 4.0\bin (click OK 3 times to get out of there).
The above step will just allow you to type 'javaloader' from wherever your command-line location is - this saves on a few steps.
A few common commands with Javaloader are: javaloader -usb load <module>
This will allow you to load an application manually without the need for Application Loader. The module name will be the name of the .cod file (for example, a theme file). javaloader -usb erase -f <module>
This will allow you to erase an application you have loaded onto the handset. In the event the application is currently being used, the -f flag forces the erase - this usually requires a restart of the handset after being run (your handset will tell you). The <module> name can be found by going to Settings > Applications > trackwheel then Modules.
Those are the two most commonly used commands - basically install/uninstall.
Let's say that you have downloaded the latest and greatest theme file for your 7100 and you want to load it. Let's say that you saved it to your Desktop. Provided you did step #2, you can bring up a command prompt (Start > Run > type cmd > OK) and type 'cd Desktop' then 'javaloader -usb load latest_and_greatest_theme.cod'. Voila.
Hope this helps.
*edit: Another useful command line, if you want to uninstall the OS from your handheld, will be: javaloader -usb wipe
This is useful for when you just want to uninstall the current OS and reinstall or downgrade (or upgrade to a new version). Be sure to backup your handheld (if possible) prior to doing this command. This will result in a JVM Error 507 (no applications/OS). You will then be able to install the OS to your machine then to your handheld (via Application Loader; I have not personally tested an OS install with javaloader and don't plan to either.. heh).