[XeTeX] basic question: small caps

[brindle at stud.ntnu.no]

I looked at the fontspec documentation (p.6), searched the archive  
(thread on Small Cap) and the net but wasn't able to get what I  
wanted. I'm not very demanding: I just need a font which displays  
nasalization and tones together correctly (those are superimposed  
diacritics). Doulos SIL does it and I can make it work like this

\usepackage{fontspec, xltxtra, xunicode}
\setmainfont{Doulos SIL}

but it can't display small caps (with \textsc{bla}). I used

\setmainfont{Junicode}

then the small caps appear but the tone/nasalization isn't right  
(another reason is publishers' formating, and I don't want to get  
stuck with Junicode just because it is the only font that works for  
me, I need the flexibility which you all seem to enjoy!). Those are  
True Type fonts.
I guess the problem goes down to what is available on my machine  
(Ubuntu 8.04), and my knowledge of fontspec, XeteX, etc.. I tried all  
sorts of things. Now I need help. Can one or some of you give some  
basic tips on how to get small caps, while being able to use DOULOS  
SIL or any other fonts which handle superimposed diacritics?




PS: Where can we purchase the book XeteX for non-geek?