Hi,
This might be a silly question but why would you want to plug a blackberry device directly into the BES server?
You have two better options, the first is to use wireless activation which would not require you to attach the blackberry device to anything.
The second is to use the Blackberry client software on a PC and connect the device there.
As an aside you should definitely consider upgrading to the latest version of BES service pack as there are known vulnerabilities in the PDF attachment reader that are fixes in SP6.
Before upgrading to SP6 consider upgrading all of you devices to the latest firmware (backing them up first of course).
Cheers,
Plod