Also try the Get Gradient* and Set Gradient* options.
1. Lay out your long and winding route at baseboard level with spline points wherever necessary.
2. Set Gradient of each segment to, for example, 1%.
3. Smooth the splines.
If you started with a 1% grade and didn't achieve the total elevation you wanted, repeat step 2 with 1.2 (or whatever)%. Repeat step 3.
If you still haven't achieved the desired elevation, stretch out the total length of the route by dragging the spline points further apart and repeat steps 2 & 3.
*These are the second row of options in the Advanced dropdown.