beatLength and \times n/m {}

[paul]

I have a little problem with beat length which appears to have
 been discussed in the past, nonetheless I 
cannot get the result I want.
I have simple music in 2/4 time and need to display, per 1/4 note,  
sextuplets of 1/16 th notes. 

Ordinarily this is simple but I would like to have 
the six 16th notes appear as three groups of
 two, not one group of 6. I have tried the
 following to no avail

\autoBeamOff
\set subdivideBeams = ##t
\set beatLength = #(ly:make-moment 2 16)
\times 4/6{c16 c c c c d}

Perhaps there is something pedantic about doing this 
inside a \times n/m {} construction ? 

Apologies if this is a trivial oversight on my part. 

Paul