You don't need to buy any third party software.
Here's the fix (thanks for Kormac for posting this in another thread):
This can be enabled on your BES. It affects all users, so talk to your BES admin. It requires BES 4.1.5+.
Check out RIM's documentation here: Turn on or turn off the Enterprise-Only Message Application icon in BlackBerry Enterprise Server software version 4.1.5
Also note that by default the icon is labeled "Desktop" (what a horrible default name RIM) - unless you go into Desktop Manger and change the name (Desktop Manager -> Email Settings -> Advanced, "Message service display name").
You can change it for all users on the BES by updating the Userconfig table in the BESMgmt database directly (the column name is "ServiceBookName"). I haven't seen this recommended by RIM, but I've had no issues changing it. YMMV.
You will need to resend the BES service books for the change to take effect.
* I have implemented this in our enterprise and it works as advertised.