Hi Alex,
These are Windows PCs yes?
Assuming they are...
If the machines are part of an Active Directory domain, it should be possible to use Group Policy [1] to push the latest version of OMERO. As far as I know you'd probably need the clients to be packaged up into an MSI file, though this is probably achievable [2] - I'm not sure if anyone's done this. This option certainly relies on having the IT infrastructure management in place.
Depending how frequently your users are working with OMERO, suggesting they always use Webstart (as Jean-Marie suggests) may be an easy win, as it'll always deploy the correct version from the server. However the trade off here is that it'll take longer for everyone if they have to wait for the client to download, so maybe a rather blunt-object approach. [3]
And yet another option would be to place the Insight folder on a shared folder on the network. Each person running Insight will be running it on their local JVM, so this should work okay, and is certainly worth trying.
[1]
http://www.techrepublic.com/article/automate-the-software-management-and-upgrade-process/6032075[2]
http://www.wikihow.com/Create-a-MSI-File[3]
https://www.openmicroscopy.org/site/support/omero4/users/client-tutorials/insight/getting-started.html#using-web-startBest,
Kenny