tsearch2 dictionary that indexes substrings?

Hi,

In this http://archive.netbsd.se/?ml=pgsql-hackers&a=2006-10&t=2475028
thread Teodor Sigaev describes a way to make tsearch2 index substrings
of words:

> Brain storm method:
>
> Develop a dictionary which returns all substring for lexeme, for
> example for word foobar it will be 'foobar fooba foob foo fo oobar
> ooba oob oo obar oba ob bar ba ar'

Did anyone do that already?

If I understand it correctly such a dictionary would require to write
a custom C component - is that correct? Or could I get away with
writing a plpgsql function that does the above and hooking that
somehow into the tsearch2 config?

thanks, Til