DOCBOOK-APPS: different depth of TOC for different elements

Hi all:
does anyone know how to make TOC's for different elements (book, part,
chapter...) have different depth? I.e., I want TOC for the book only
show parts, chapters, and appendices; TOC for part - only chapters; TOC
for chapters - sect1 and sect2...

Dave Pawson's FAQ page 
http://www.dpawson.co.uk/docbook/styling/params.html#d60e59
lists this same question and says 

>You'd have to create a customization layer that defined a new parameter
>and a modified TOC-generating template to use it. The TOC machinery is
>not simple, however. This would make a fine feature request, though.8^)

I looked through TOC machinery and am not eager to customize it - I am a
newbie. But maybe someone has created such a customization layer since
this FAQ was written?

Thanks in advance!

Sasha