DOCBOOK-APPS: keyword in index of htmlhelp

How can I customize htmlhelp rendering (<xsl:template name="hhk">) to generate
index for htmlhelp from keywords placed in sectioninfo structures? How can I
force to create automatic index just like ToC is created for other formats. Is
there a simple switch for it or it requires advanced "hacking" ?

Wlodzimierz Skiba