Revit :: Sidewalk / Garden Paths In Arch

I just did a competition that required a garden.  Lacking time to fully research Revit options, I ended up creating a topo and cutting paths into it by using building pads for the paths, requiring a lot of tinkering with the topo elevations.  This was far from ideal because I wanted to alter things later, but it was just too labor intensive to do that and I ran out of time.
 
Any (cheap!) program that would work well for this?  Something that could export a file that could be linked into Revit?
 
It would be very nice if a version of "building pad" could be created by Autodesk that would work as a sidewalk/path and that could also have a slope.
 
Another problem with this was that I had to position all the topo points along the path wall borders at a low elevation because the topo "bled" into the walls as it sloped up from them.  Another great thing would be if Revit sidewalk pads could have borders that also "cut" topo.