Function RouteFileRecordAddCustomSection(Xlong1,Ylat1,Xlong2,Ylat2: double): integer;
This will add a custom section to the current record. A custom section doesn't have to be a part of the existing street network, but can be anything such as the off-road section from a coordinate to a location.
You should call this function as many times, as you have defined in the call to RouteFileRecordAdd, the numsections parameter.