I was unable to get the API calls to work to print drawings from VB. I also had problems getting Pro/E to print from a macro with no_graphics mode turned on.
The solution I finally came up with is to use Pro/E to print to a .plt file and then run the plotter command (as found in the .pcf file) directly on the .plt created by Pro/E. It may not be elegant, but it works with everything I've thrown at it.
The algorithm looks something like:
For each drawing to be printed
____Switch Pro/E's working directory to the directory of the drawing
____Open the drawing
____Run a macro to print the drawing to a .plt file
____Close the active Pro/E window
____Clear all undisplayed models from memory
____Call the plotter command in the appropriate .pcf file to print the .plt file