[XeTeX] XeTeX 1.0 - request for comments

[musa furber]

<Unnamed commercial font> is my font of choice. It doesn't have  
glyphs for ḍ, ḥ, ṣ, ṭ and ẓ. I would have preferred the TeX- 
only solution of drawing a dot under a letter, but I couldn't find a  
way to change the dot's placement based on whether the font was roman  
or italic. My "solution" was to make a modified version of the font  
using FontForge. The kerning tables in the modified version are  
damaged, but the glyphs I want work so I just use active codes to  
switch to modified font as needed.

I really would prefer being able to solve this without having to go  
outside XeTeX. (If it can be done in XeTeX, then I would rather learn  
something about XeTeX instead using a tool about which I am even more  
grossly ignorant.)

I can understand how tampering with the given font metrics may not be  
in the spirit of XeTeX. But would a mechanism for making these  
trivial compositions really violate that spirit?

Regards,
Musa