It is possible to configure the colors and icons in two lists in the source of the python script: 
                   # ccode  colo[u]r   name       html-open   -close
color_codes_info = [ ( 0, '#000000', 'default',       '',    ''     ),
                     ( 1, '#000000', 'directory',     '', '' ),
                     ( 2, '#000000', 'unknown files', '',    ''     ),
                     ( 3, '#00DD00', 'executables',   '', '' ),
                     ( 4, '#009999', 'text files',    '',    ''     ),
                   ]

                   #  ext   ccode  description           icon
extensions_info = [ ("py",   0, "Python source"    , "textfile.png"),
                    ("py~",  0, "Old python source", "textfile.png"),
                    ("pyc",  0, "Python byte code" , "textfile.png"),
                    ("pl",   0, "Perl source"      , "textfile.png"),
                    ("c",    0, "C source"         , "textfile.png"),
                    ("cpp",  0, "C++ source"       , "textfile.png"),
                    ("cc",   0, "C++ source"       , "textfile.png"),
                    ("java", 0, "Java source"      , "textfile.png"),
                    ("class",0, "A class file"     , "textfile.png"),
                    ("ply",  0, "plynets data"     , "somefile.png"),
                    ("txt",  4, "Text"             , "textfile.png"),
                    ("gz",   0, "GZ archive"       , "somefile.png"),
                    ("tar",  0, "TAR archive"   , "somefile.png"),
                    ("tgz",  0, "TAR GZ archive"   , "somefile.png"),
                    ("png",  0, "Graphics / PNG"   , "gfxfile.png"),
                    ("gif",  0, "Graphics / GIF"   , "gfxfile.png"),
                    ("jpg",  0, "Graphics / JPG"   , "gfxfile.png"),
                    ("jpeg", 0, "Graphics / JPG"   , "gfxfile.png"),
                    ("tif",  0, "Graphics / TIF"   , "gfxfile.png"),
                    ("tiff", 0, "Graphics / TIFF"  , "gfxfile.png"),
                    ("tga",  0, "Graphics / TGA"   , "gfxfile.png"),
                    ("ico",  0, "Graphics / Icon"  , "gfxfile.png"),
                    ("html", 0, "HTML"             , "htmlfile.png"),
                    ("htm",  0, "HTML"             , "htmlfile.png"),
                    ("iso",  0, "ISO image"        , "somefile.png"),
                    ("img",  0, "Floppy image"     , "somefile.png"),
                    ("pdf",  0, "Portable Document format"  , "somefile.png"),
                    ("bat",  0, "DOS batch file"   , "textfile.png"),
                    ("exe",  0, "DOS executable"   , "textfile.png"),
                    ("com",  0, "DOS executable"   , "textfile.png"),
                    ("dll",  0, "Windoze library"  , "textfile.png"),
                    ("ogg",  0, "Music / Ogg"      , "textfile.png"),
                    ("mp3",  0, "Music / MP3"      , "textfile.png"),
                    ("bak",  0, "Old version"      , "somefile.png"),
                  ]
default_extension_info = ("", 0, ""   , "somefile.png" )
If you want to make your own files take "somefile.png" as template.

Future plans: