Yeah, just go slow, think logically and have the car in neutral so you don't run-over yourself when you "bump" the starter. Hey, that brings up another situation: I don't know if you car has a safety switch to where the clutch has to be pushed-in before the starter circuit is complete? You may have to bridge that switch too while someone operates the ignition switch. That would be another one to check IF the starter cranks over when you "bump" it. (* On the newer Toyotas there is an override button on the panel which will allow the starter to bypass that safety switch. See if your car has one of those. That switch was put there in the event that the safety switch became defective.) Or if you have an automatic transmission, there is a switch which will only allow the starter to crank in Park or Neutral. Both switches are easy to find. That switch would be between the relay and the starter.
When it comes to "bumping" the starter over, all you need are a couple of 10 gauge wires about 10 feet long. The Negative wire would be held against the starter body. The Positive wire would be touched against the small wire terminal at the starter, or even the large positive terminal on the starter. A large clamp on each wire to connect them to the battery would be nice unless you can have someone hold them on the battery terminals. Radio Shack sells large enough clamps for a couple of dollars.
My gut feeling is that your battery cables are probably corroded. I hope that it's that simple.