TOC in output plugin

[HANAX]

I was told that durin processing there is a TOC build. How I can acces it in my 
XSL file? Or another way: how can I access list of sections and transform it 
into list of elements in head of XHTML while processing my xsl file?
I've started with text plugin as example but it's little bit complicated for 
me, can anybody recommend me simpler example?
And last, if I want to use XHTML serializer, it gives me an error "Type 'xhtml' 
does not exist for 'map:serialize'". Why?