Hi,
There is no option for using templates. If you have a alignment (in plan and profile) you easily can create features representing channel bottoms. Use CadTools command "Offset 3Dpolyline" to create left and right edges of the bottom, use "Create Longitudinal Features" to get the line that interfere with the surface. Finally you triangulate these four lines as breaklines and save it as a surface file. When creating cross sections add that surface.
If you don't have a 3D alignment read in the helpfile how to create a 3D alignment from a line in plan and a line in a profile, "Create 3D alignment"
If you get unwanted triangles you can join the outermost lines to a perimeter and use it to delete triangles outside the perimeter, Look in the helpfile "Delete triangles with centroid outside polygon"
/Lars