ETS integration is mainly for an engineer who has the ETS on their desktop to be able to launch the tools while browsing their Orion server. It's not meant for installing the toolset on the server and allowing multiple people to run it from there.
That being said, someone did work on a way around that - you can find it here, not sure if it works for all tools though. I'd bet not....
Haven't tried it myself, and looks like he's only done it with a couple things...
I came across that link as well. I thought I found somewhere that there was integration if it was directly installled. I do have the Toolset installed on my desktop, and I was having problems with getting the integration to work. I finally found that I needed to have ToolsetIntegrationTray running on my machine to get the full integration.