I have never figured out how to just start laying pipe in and have it sloped. I always have to use design line and set the design line at 1/8" slope (1:96). When using the design line though make sure you go to >Line>Drainage Tool and the software is usually pretty good at finding the lowest point but I always click Define Source just to be safe. Don't mess with the Set Pitch Pont button, just select the 1:96 from the Fall dropdown menu (1/8" per foot). click OK and you should be able to look at a side view and see your Design Line sloping. If it is then click the Fill In 3D button and you are rocking except the software sucks at trying to put in wyes and just leaves them blank so most of the time you still have to go and put those in manually, but when you do put them in they will be sloping with your pipe.

O/T Does anyone know why they have slope in engineer scale in ratio (1:96) instead of architect scale (1/8"). Also, If anyone knows a way that you can just start dropping pipe in at a slope (similar to Fabrication Parts in Revit) I'd love to know too.