Hi berksgr,
As Viscosity is controllable via AppleScript you could use a custom script or a third party application to tell Viscosity when to connect. Three apps that I know of that should work are:
Home Zone - http://mac.softpedia.com/get/Security/Home-Zone.shtml
MarcoPolo - http://www.symonds.id.au/marcopolo/
Sidekick - http://oomphalot.com/sidekick/
Details on controlling Viscosity via AppleScript can be found at:
http://www.sparklabs.com/support/controlling_viscosity_with_app/
Cheers,
James