Should it work to cut fuel pump power in case of an accident?
NO
Inertia switch is there to cut power in a sudden stop or roll over.
If you want to by pass it you just hook the wires together, no fuse is needed, circuit for fuel pump power is already fused in the engine compartment.
Fuel pump power runs like this:
Battery------Power box or starter relay---30amp fuse(or fusible link)-----Starter Relay-----inertia switch------Fuel Pump
The Fuel Pump Relay will be under the Power Box if you have one or mounted on the passenger side inner fender, it will have a Green Base that the relay plugs into.
There are often 3 relays in a row, Brown base is EEC relay, Black base WOT relay(wide open throttle).
The computer activates the Fuel Pump Relay to send power to the pumps(you have 2)
It does this by Grounding the Relay.
There is a way to test relay using the OBD test port in the engine compartment
Look here:
http://www.therangerstation.com/tech_library/OBD_I.shtml
Look at the diagram of the connector
If you Ground the slot labelled Fuel Pump with key on, you should hear the fuel pump relay close(click) and if the other wiring is OK fuel pump should come on.