Headline - Symbol List.tmPreferences

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <key>name</key>
   <string>Symbol List</string>
   <key>scope</key>
   <string>meta.function.headline.latex</string>
   <key>settings</key>
   <dict>
      <key>showInSymbolList</key>
      <integer>1</integer>
      <key>symbolTransformation</key>
      <string>
        s/\\headline\{([^\}]*)\}/H $1/g;
      </string>
   </dict>
</dict>
</plist>

LaTeX with Headline.tmLanguage

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>fileTypes</key>
    <array>
        <string>tex</string>
    </array>
    <key>name</key>
    <string>LaTeX with Headline</string>
    <key>patterns</key>
    <array>
        <dict>
            <key>begin</key>
            <string>(\\(?:headline))(\{)</string>
            <key>beginCaptures</key>
            <dict>
                <key>1</key>
                <dict>
                    <key>name</key>
                    <string>support.function.heading.latex</string>
                </dict>
                <key>2</key>
                <dict>
                    <key>name</key>
                    <string>punctuation.definition.headline.begin.latex</string>
                </dict>
            </dict>
            <key>contentName</key>
            <string>meta.headline.latex</string>
            <key>end</key>
            <string>\}</string>
            <key>endCaptures</key>
            <dict>
                <key>0</key>
                <dict>
                    <key>name</key>
                    <string>punctuation.definition.headline.end.latex</string>
                </dict>
            </dict>
            <key>name</key>
            <string>meta.function.headline.latex</string>
            <key>patterns</key>
            <array>
                <dict>
                    <key>include</key>
                    <string>$base</string>
                </dict>
            </array>
        </dict>
        <dict>
            <key>include</key>
            <string>text.tex.latex</string>
        </dict>
    </array>
    <key>scopeName</key>
    <string>text.tex.latex_with_headline</string>
</dict>
</plist>