I don't think putting a jumper on the pins would work because the switch is probably the pulse kind. It doesn't stay connected all the time like a jumper on the pins would. It just makes a connection for a short time telling the mobo to turn on the PS. I've never tried the jumper thing, so I can't say for sure if it'll work or not. I'm guessing your switch is the electronic kind and not the physical toggle. If it is the kind that has a post coming out of it that clicks in and out, then you could cut the two wires coming out of it and just brush them together to turn it on. It'll be easier to help if we know exactly what kind of switch it is. If the switch is irreparable, you can always get another switch and replace it.
Yeah, momentary, not pulse. That's what I meant.