It would be impossible to add all the endpoints to the tor network since the network topology is dynamically created. In essence everyone can be a tor node.
Think of it like P2P, distributed transacting which ensures that no particular host can be identified as the origin or source of the data.
In fact, the whole idea of tor (and onion routing in general) was to address this issue. It was initially put together by the US Navy to allow dissidents in China to bypass the 'great firewall of China'.
It would depend on how the protocol tunnels through the network. If the Websense Network Agent is installed on whatever server its going through, then as long as a UserAgent or some other identifyable factors are used to indicate the tunnelled traffic, it will be blocked.
Websense has the "Proxy Avoidence" category in its URL Database to stop access to the online ones that are through a web browser.
Websense also has the "Proxy Avoidence" category in its Protocol Database to stop anything from either using specific ports or tunnelling traffic. I would probably guess that its blocked in the Protocol Database.