Are you wanting to use two connections at the same time here? Windows to use the LAN connection, and a specific application (firefox) to use the mobile broadband?

Yes thats exactly what i need :)

I'm not entirely sure you can route network traffic from one application to a different connection (not on Windows anyhow).

I'll look into it! :)

Bump :)

I'm also very interested in this!

WiFi connection to be used by Mozilla and default Win connection(cabled) should be used for everything else.

Not all windoze versions are capable of using two "connections" simultaneously.

With some additional software you could conceivably route firefox traffic by configuring your respective firefox proxy settings.

or pay a third party for proxied traffic. something akin to:

https://www.ipredator.se/

this is not exactly a solution to your question but I wager it is more likely preferable to-you.