You can either run the line to the MAP sensor hose (what most people do) or you can run it to the hose right off the compressor housing. Either way your gunna need to build a T with 2 barbed fittings at each end for the hoses for the MAP and then a compression fitting for the gauge.
Just get the barbed fittings to fit the hose correctly and then the compression fitting might be a little difficult to find but I got one at Advance from a boost guage install kit they had. You can find the T and Barbed fittings at your local hardware store and if you're lucky they'll have the right size compression fitting.