As Willie pointed out, the work is being done in Globe AZ where were are running a winter season excursion train. The train is currently diesel powered. This has been covered in past posts, so I won't go into that here.
The CML #3 is way to small and slow to be of use over the La Veta. While no offical plans have been made for its use after the Arizona Eastern passenger season ends in early May, It would not suprise me to see it shipped to Alamosa for the summer and used on the mixed train to Monte Vista a couple of times a week.