You quoted I have to manually put in each coordinated Cogo point (from old plans)
So why not make a csv file with P,E,N,Z,D if your picking points from a existing plan what do they have, are they on a layer and with z's.
By picking you can look at stringing the code using a while pick say edge of bitumen in sequence, so P,E,N,Z,001EB gets created the other side would be P,E,N,Z,002EB so the 2 sides do not join.
Can you post a old plan dwg. May be able to do something with it.