Hi
Please see the following website.
Enabling BitLocker on Removable Drives (USB Flash drives, USB Hard Drives):
http://blogs.msdn.com/askdavid/archive/2007/06/08/enabling-bitlocker-on-removable-drives-usb-flash-drives-usb-hard-drives.aspx
I'm not absolutely sure about this, but I believe it is possible. I think all you would need would be the encryption key on the other system. You might want to check the following documentation.
BitLocker Drive Encryption Step-by-Step Guide:
http://technet.microsoft.com/en-us/library/cc732725.aspx
Hope this helps.
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Ronnie Vernon
Microsoft MVP
Windows Desktop Experience