\startsetups mp:instance:one
    indeed:\space
\stopsetups

\setupMPinstance
  [metafun]
  [textstyle=bold,
   textcolor=darkgreen,
   setups=mp:instance:one]

\defineMPinstance
  [mympinstance]
  [metafun]
  [textcolor=red]

\starttext

    \startMPcode
        draw textext("some text") ;
    \stopMPcode

    \startMPcode{mympinstance}
        draw textext("some text") ;
    \stopMPcode

\stoptext
