documentclass[a4paper]{article}

usepackage[autodefine]{xspotcolor}
NewSpotColorSpace{PANTONE}
AddSpotColor{PANTONE} {PANTONE3035PC} {PANTONESpotSpace 3035SpotSpace PC} {1 0 0.05 0.72}
definecolor{PANTONE3035PCA}{spotcolor}{PANTONE3035PC,.5}
definecolor{grey}{gray}{0.5}

usepackage{fontspec}
setmainfont{Linux Libertine O}

begin{document}
SetPageColorSpace{PANTONE}

Examples:

begin{itemize}
  item this text is not Pantone
  item textcolor{PANTONE3035PC}{dark blue}
  item textcolor{PANTONE3035PCA}{light blue}
  item textcolor{grey}{grey}
end{itemize}

end{document}