The old way around Santa Fe, NM, began in the San Juan's of Colorado -- specifically the areas of the Animas and San Juan rivers. Then it headed south to present day Grants, NM.
There use to be an old Spanish settlement at San Rafeal just South of Grants. From there it would travel down the east side of the lava flow from where they could cross over into Alamacito Creek. That would take them east to the Rio ?Grand River, not too far north of the old Mission at Socorro, NM. From there it was a straight trip south into Mexico. I am sure that there was an eastern route as well. No one wanted to go through Santa Fe heading south. The taxes demanded by the governor were quiet high.