I searched the CGW Group that I mentioned above. Here is my understand so far:
On the north end of St. Joseph, the CGW ended at a switch with the CB&Q at around Francis Street (or thereabouts).
CGW trains traveled through St. Joseph via trackage rights over multiple railroads.
At the south end of St. Joseph, the CGW ended at a switch with the Santa Fe at Bee Creek Junction, which is visible on this large map. WARNING: This map is a big file and takes some time to download.
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www.lib.utexas.edu]
I recommend joining that CGW discussion group. The folks on there are tops.