\definehead[one]  [section] [style=\sl]
\definehead[two]  [one]
\definehead[three][two]
\definehead[one]  [chapter] [style=\bf]
\definehead[four] [one]

\starttext

    \usemodule[structure-sections]

    \showstructuresections

    \one{section-one->chapter-one}
    \two{section-two}
    \three{section-three}
    \four{chapter-one}
    \four{chapter-four}

\stoptext
