[XeTeX] Language-specific glyphs

[Dragan Zlatkovic]

Many of the Adobe fonts (Warnock, Minion, Garamond Premier) contain
cyrillic glyphs for the Serbian cursive forms of de, pe, te and ghe.
However, I can't access them via \addfontfeature{Language=Serbian}. In
InDesign I add them manually (Glyphs -- > Alternates for selection).

\XeTeXglyph probably works (I haven't tried it yet) but is there some
simpler way?

Dragan