[XeTeX] Active dash or interchartoks?

[Will Robertson]

On 2009-10-01 07:08:03 +0930, "Joel C. Salomon" 
<joelcsalomon at gmail.com> said:

> 	\catcode`\—=\active
> 	\let—=\dash

That looks vaguely like something I've written in the past :)

> What are interchartoks, and how would I do this with them?

There's an example in xetexref that might help to get you started. 
(Although the feature wasn't really designed for this sort of 
application, in a controlled environment you can get very good results 
from it.)

Will