I'm not familiar with your bike so I don't know how the tank gets mounted (large hose clamps?).
In answer to your question of how to hook up the fuel line, there are a number of options offered on ebay. The black rubber bushing gets pushed into the existing hole in the bottom of your tank and then the valve gets installed into the bushing hole, causing it to expand which keeps the valve in its place and not let gasoline to leak.
192980GS Fuel Shut Off Valve Service Kit w/ Grommet Bushing Plastic Gas Tank
US $5.99