This tool (and probably yours if it is different) works on most of the modern external cup BBs including Sram & FSA:

http://www.parktool.com/product/bott...ket-tool-bbt-9

What model of shimano crank/bb do you have now? If you just want it out and are going to be installing something modern you may do just as well to have an LBS do it as you won't need the tool after that.