Ok, this is a two part process that wasn't clear, at least to me.
First, in Virtual Weather Station, turn on Settings, CVS Export, then check Create csv output file. Now VWS is putting the data out there for ImageSalsa.
Second, you point Image Salsa to the cvs output file and everything works.
In my case, the data lives in C:\Program Files\vms\data\csv and the datafile is called data.