Venting a pump question please

[tye]

Hello...I am running a 1 1/2 inch pvc drain line from a new kitchen sink in my basement into a liberty 404 pump which is sitting on the basement floor. The pump has a drain hole on the side (which I tapped into for my drain line) and another 2 holes on top for the vent line and discharge line. I have run my 1 1/2 pvc discharge line over to the main 3 inch stack and tapped into that. And I have located a 1 1/2 pvc vent line running up from a tub/shower in the same area of the basement. So can I tap into that vent line for my pump vent? If so, at what height do I need to tap into that? My discharge line goes 6 feet vertical from the pump and then slopes over to the main stack for the discharge. Venting just confuses me all the time and I don't want to screw this up. Any experts out there that could help me with this venting problem would be greatly appreciated.