Pole Position Club is not really a mission at all, although you still need to complete it.
When you’ve purchased the club, all you then need to do is to enter the club and walk through until you reach the corridor on the far left.
When you’ve reached the corridor go into the room on the left as seen in the picture and, erm, one of the staff will dance for you for money.
To complete the mission, you just have to sit there and watch the dance until you’ve paid $300 in total. It costs $5 per 5 minutes of game time, so you may want to go and make a cup of tea unless you’re enjoying the dance that is. You can exit and come back any time as long as you spend $300 in total over the course of your visits. To add a little variety, if you exit mid-way through you’ll get a different dancer to entertain you.
Once you’ve done so, exit the room and you’ll have completed the mission. You’ll also have ‘unlocked’ a room further down the corridor with a more enthusiastic cowgirl dancer!