My understanding is you already have a set of JAD/ALX/COD files. Depending on your requirement. This application can be pushed via software configuration by the administrator as the BES account gets activated "OR" you wanted it that it is the end users who downloads the file from a web server hosting the JAD files.
You needed the scenario above to work and documented properly so that your users will be able to follow the instruction the easiest.
I am a BlackBerry Certified Systems Administrator. I have extensive support experience regarding software configuration and application push.
Please let me know if I will be able to help.