\showinjector

\setinjector[register][3][\column]
\setinjector[list]    [2][{\blank[3*big]}]

\starttext
    \placelist[section][criterium=text]
    \blank[3*big]
    \placeregister[index][criterium=text]
    \page
    \startsection[title=Alpha] first  \index{first}  \stopsection
    \startsection[title=Beta]  second \index{second} \stopsection
    \startsection[title=Gamma] third  \index{third}  \stopsection
    \startsection[title=Delta] fourth \index{fourth} \stopsection
\stoptext
