[XeTeX] Faking small caps?

[BPJ]

I have a text where certain words should be set in small caps. The 
problem is that some of these words contain the character ŋ, which 
isn't supported in small caps in the font used.  Might there be 
some way to fake a small cap ŋ in these words -- preferably 
smarter than search-replacing ŋ with {\small Ŋ} in those words?  I 
already use a semantic custom command, \let to \textsc for those 
words, so a solution which 'automatically' replaces ŋ with 
something suitable inside that command would be preferable, but 
I'm not sure to achieve such an automatic replacement, nor what 
the smartest replacement may be. Leaving ŋ as lowercase looks 
absolutely horrible!

TIA,

/bpj