Print First Page for Multiple PDF's

Dears,

I am using the below script (which I found online) to print the first page of multiple PDF's. It is working great, but the only thing missing is that I need to print in grayscale. Can anyone help? Below is the script:

/* Print 1st Page */

/* This sequence prints the first page of

each document selected to the default printer.

*/

this.print

({

bUI: false,

nStart: 0,

bSilent: true,

bShrinkToFit: true

});