Sims 2- Pool above the first floor

Hi,

I'm new here, but I'm a big fan of The Sims Series from a long time and I saw a post that speak about pool above first floor   http://modthesims.info/t/83325 ... I tried to  do that, but it is freaking impossible !! No tutorial, unfortunately, but is there some Sims 2s professional that could do that ? Thanks,

-AlexManGarden