Using ligatures from Linux Libertine for numbering sections and in TOC

Using ligatures from Linux Libertine for numbering sections and in TOC References The old Libertine package, which worked with pdfTeX, included a command \\libertineGlyph{}. \\libertineGlyph{Fourroman} printed â…£ But how can I get these roman numbers used for numbering sections and even in the TOC? I found Using ligatures from libertine for roman numerals in pdftex , but I do not know how to make it work. MWE: \\documentclass[ngerman]{article} \\usepackage[T1]{fontenc}\\usepackage[utf8]{inputenc} \\usepackage{babel,blindtext} \\usepackage{libertine} \\newcommand*{\\libertineRoman}[1]{% \\def\\Romantemp{}% \\ifnum\\value{#1}>0\\relax% \\ifnum\\value{#1}<13\\relax% \\edef\\Romantemp{\\ifcase\\value{#1}\\or One\\or Two\\or Three\\or Four\\or Five\\or Six\\or Seven\\or Eight\\or Nine\\or Ten\\or Eleven\\or Twelve\\fi}% \\libertineGlyph{\\Romantemp roman}% \\else\\Roman{#1}\\fi% \\else\\Roman{#1}\\fi% } \\newcommand*{\\libertineroman}[1]{% \\def\\Romantemp{}% \\ifnum\\value{#1}>0\\relax% \\ifnum\\value{#1}<13\\relax% \\edef\\Romantemp{\\ifcase\\value{#1}\\or one\\or two\\or three\\or four\\or five\\or six\\or seven\\or eight\\or nine\\or ten\\or eleven\\or twelve\\fi}% \\libertineGlyph{\\Romantemp roman}% \\else\\roman{#1}\\fi% \\else\\roman{#1}\\fi% } %%% Roman numbers \\renewcommand{\\thesection}{\\Roman{section}} %%% Roman ligatures from Linux Libertine? %\\renewcommand{\\thesection}{\\libertineRoman{section}} %%% DOES NOT WORK \\begin{document} \\tableofcontents{} {\\libertineGlyph{Fourroman}} \\blinddocument \\end{document} Cave: I use the old libertine package from years ago, which provides \\libertineGlyph for pdfTeX. However, maybe somebody can give me a hint.