You could deploy the workflow as a web service and call the webservice via a generated WS component. Optionally, you could turn this workflow into a decision project, publish it as an executable, and call it using the Shell Execute component.

I made a .exe and it shows the input var when I run it at the command line, then it says it completed successfully but doesn't give me output. When I use the Shell Commands component in the workflow I am trying to call it from, it returns the following:

Name: System.String[]
Command: System.String[]
Arguments: System.String[]
CommandToExecute: System.String[]

and Workflow considers those vars singles, so I can't use the array functions like "Build Text from Elements"

Have you tried going the web service route? I completely overlooked the fact that this returns output. Usually I go the web service route for stuff that outputs stuff, and executables for workhorses that don't return output.

This worked for me, and is a reasonably eloquent way of pulling it off, thank you!