its hard to get a wire through the grommet where all the factory wires run. Sometimes there is an empty grommet in the firewall that you can poke a hole through and run your wire through that. Dont limit yourself to the driver side of the firewall either, check the passenger side too. Or if its really bad, you'll have to carefully drill a hole and pop a new grommet in it.

Is there any way you can run the wire to the engine bay fuse box, to save hassle??

whats the wire for?

I wouldnt advise running wires under the car.