In the past, Photoshop would allow us to direct the current Photoshop version to access plug-ins located in previous Photoshop versions. This was done in Photoshop preferences. I cannot find how to do the same within Photoshop CC 2014's preference panel. Does anyone know how I can do this?
Um, no - you should never move plugins between versions of Photoshop (which is part of why the "alternate plugin folder" had to be removed - it was almost always misused).
Just install your plugins for CC 2014, just like any other major version update.