Paul, sorry it has taken a while, but I was able to scale down the Leadville Passenger and Freight Depot parts to HO. They are also available in O and S on my Shapeways site (Poverty Flats Model Company).
The Passenger Depot windows and doors are on two sprues and one includes windows for the airlock on the west side. The roof brackets with the curved bottom chord and the dormers are available in HO and O; I still need to post the parts in S.
The Freight Depot windows and freight doors and criss-cross brackets for the trackside are available in all three scales. I did not include the man doors, as I modified my own using Grandt Line parts.
Sorry, Jeff, I have not had a chance to scale down the Kokomo sprue to HO--this window and door package is available in S and O. Also on my to-do list is to package up the parts for the Fort Logan/ Estabrook/ Dome Rock parts so you can get what you need in one easy purchase to build these cool early depots.
So go order yourself some parts and scratchbuild these two buildings. Then post photos of your builds here, because, well, we all like to watch other people work!
Keith Hayes
Leadville in Sn3