To start with: Pantone and other colours were created because the range of hues you can "mix" with CMYK is so limited. So there is no way whatsoever to re-create a Pantone hue in CMYK. An offset-printer will have to either buy the already mixed ink, or mix it himself starting with a set of basic Pantone inks.
BUT: if you own a deskjet that has more than four inks (six, or even eight) you can print an extended CMYK range.
The way this is done (I do not guarantee you get the exact Pantones! so never use this as a model to go to an offset-printer! only the pantone guide bokk if ok for this, ok?) is to trust your puter. There is no way to separate these six/eight inks yourself. You must trust your printer's software.
The printer may come with a profile, or it may need your work being in some RGB space like AdobeRGB. Do as the software asks.
I personally always use duotone to colorize images (often even the tritone, or even quadtone option) as the curves give an additional richess that is unsurpassed. Afterwards I go back to rgb, prefereably in AdobeRGB space as that is the largest, and then I print on my Cano 6 inks printer.
In case you own a four colour printer (CMYK, no adds), then you will notice loss in the bluegreens and ...oranges. But you can print anyways, and the result will be good.
So recap: set to greyscale, then to duotone, create your image and go back to RGB, prefereably AdobeRGB. Then follow your deskjet's instructions.
