The BACKUP VM command is not supported on this client (ANS1184W)

Just a heads up, so others don't run into this - TSM Integration w/VCB is not supported on x64.
As per this posting to ADSM-L by Andy many months ago:

At the time 5.5 VCB support was being developed, the 64-bit VMware VCB framework was not available (though I think one has since been introduced). So TSM support is currently 32-bit Windows 2003.

Good news is that 'backup vm' works on the x64 platform when using the x32 client.

x64 binaries - v5.5.1.0 - C:\progra~1\tivoli\tsm\baclient
x32 binaries - v5.5.1.0 - C:\progra~1\tivoli\tsm\baclient32

C:\progra~1\tivoli\tsm\baclient32.dsmc.exe backup vm -vmlist="fileserver[fileserver_fs]"