Digital BW, The Print

I recently converted a refurbished R1800 to the 3-MK workflow, and am
getting very good results printing my scanned B&W negs on Museo II. 
However, I have some Silver Rag that I would like to use in the same
printer, but I need some guidance in re: Paul R's changes to 3-MK to
do this.  From reading his method I assume that I would change the
Eboni MK in the PK position to the equivalent PK ink, and change the
MK in the glop position back to glop.  Then I would print the image
and, after drying, run the print back through the printer using only
the glop channel.  Afterwards I would over-spray.  Do I have this
right?  How does one control the printer to use only the glop channel
and nothing else?  How much better is the above workflow than simply
printing Silver Rag with the 3-MK inks, and then over-spraying?  

Thanks