...As M_Marcos has already mentioned, gaining access to a Full Disk encrypted hdd must be done using the Access/Recovery CDs in the media downloaded from fileconnect. You have to boot the machine from the CD and use the inbuilt utitilies.
If you're looking to decrypt, then you'll need the Recovery CD. Note that the below article recommends contacting Symantec support as a first step:
http://www.symantec.com/docs/TECH104300