OK, so I think I missed an important step.
This is a little closer than what you probably got, but still not there.
This is what I did. I picked a thick font, and moved the letters far away from each other. (go to character>tracking>200).
I rasterized the layer. I duplicated it twice, naming the copies RED and BLUE. I CTL+clicked each and filled it with its respective color. I created an empty layer above each colored layer.
To get the yellow, I CTL+clicked on the red layer to get a selection. I selected the empty layer above red, and filled it with yellow. To remove the yellow I didn't want, I CTL+clicked on the original white layer to select it, clicked back on the yellow layer, hit CTL+SHIFT+I to invert the selection, then hit delete. That left only the yellow that was direct above white.
I repeated that sequence for the light blue.
I merged all the text layers, and did a gaussian blue of 1.4.
I think a better font would give you more of the white letters exposed, but this isn't too bad.
Agent