mplayer + fontconfig + local.conf + relative path

[Selur]

If I use:

<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
    <dir>c:/Users/Selur/HybridFonts</dir>
</fontconfig>

as my local.conf content, mplayer/fontconfig detects my fonts properly, but when I use:
one of these:

    <dir>~/HybridFonts</dir>
    <dir>%USERPROFILE%/HybridFonts</dir>
    <dir>%HOMEDRIVE%/%HOMEPATH%/HybridFonts</dir>
    <dir>%HOMEDRIVE%%HOMEPATH%/HybridFonts</dir>
    <dir>%HOMEDRIVE%%HOMEPATH%HybridFonts</dir>
    <dir>%HOMEDRIVE%%HOMEPATH%\HybridFonts</dir>

instead of the absolute path mplayer/fontconfig does not detect my font.

-> Does any one know how I can use a relative dir for fontconfig on Windows?