So I did somethign pretty dumb and cut the cable by accident. I 'assume' I need to unscrew the three screws on the bototm of the shifter in order to get at recabling it and get a cablewitha special knob on the end from my LBS?
I've had em break off inside before. I've been able to get it out with a pointy instrument. You just have to dig at the end with the cable stop. I'm not exactly sure of your model, but often times disassembling a rapid fire shifter isn't a good idea, unless you are pretty good.
That's good news, do you or anyone else have any online pics/manuals to show me how?
I am not familiar with the shifter, but usually you work the shifter, with some tension on the cable, till it is in the small cog/ring position. Then you should be able to push the cable out through the shifter. Put the new cable in through the same hole. The Shimano website will have diagrams/instructions for your particular model.
I assume it's an MTB shifter, probably Deore or XTR...
you need to open up your shifter to get to the cable stop. shift to the smallest gear setting then push out/fish out the cable stop from the shifter cog.
you'll have to readjust your shifters/RD after this...
ParkTool has the procedures. Scroll down to the Shimano STI Shift levers section.