If I understand you correctly, you want to colorize the selected colors with tints of the same pantone color?
If so, you need to create a color group with all the tints of the pantone color. One way to do this is to create a blend with specified steps between two tints 100% and 0% of a pantone color. If you choose 100 steps after you expand the blend you will have 100 tints of the same pantone color. While selected, from the menu of the Swatches panel choose New Color Group and in the dialog check Include Swatches for Tints.
In the Recolor Artwork > Recolor Options, for Colorize Method choose Preserve Tints. Then back to the Recolor Artwork window, on the right side, in the Color Groups pane, click the color group with the tints of the pantone color you created.
