Distance traversed in a route

[Sreejith AC]

Hi,
 
 I am developing an app which lets the user create custom walking routes. The input will come from his pedometer as steps he has covered, which will be approximated to distance (as meters or km). I need to show the progress (distance covered) in the map, along with the route. I thinking of a layout as a green path for the actual route, overlayed by a red path indicating the portion that he already covered. Is it possible to

a) create two direction overlays over the same path, but two different colors (Same starting point, but ending points will be different, both falling in the same path)

b) create a direction path with way points specified. i.e From point A to point X, google maps may select A->B->C->X. But user wants A->B->D->F->C->X.

Thanks
Sreejith