Fill-in flash with M6?

[ohtonen.2@swsgen01es.ntc.nokia.com (Ohtonen Pasi)]

I think this topic is almost heretic on this list, but...

The main reason for me for getting an M6 is shooting
in available light. However, there are situations, where
a modern p&s camera - like the Leica Minilux or Leica
Mini would be a better choice - simply because of the
flash capabilities.
Now, it would be the easiest solution to own both the
Mini and the M6, but it has would divert my shots to
two different cameras - the other would be used for
exposing 30 rolls of film per year and the another only
for 1..2 rolls per year. I don't think it would be a good
solution for me.
I would like to find out, how to get the "modern" fill-in
flash effect with M6, just enough to stop the movement,
with 35mm lens, from the distance of - say - 1,5 to 3
meters (indoors), shutter at 1/8 sec .. 1 sec and f-stop
according to...?

Here are my points of concern:
 - does the X-sync of Leica M6 work with slower shutter
speeds than nominated 1/50 sec setting? This is
really the main issue.
 - Are there any flash units that contain adjustable "delay"
for getting the sync near to the trailing edge of the shutter?
The latter would be a nice "plus".

I was thinking to underexpose from one to two f-stops from
the M6 meter reading and fill the gap with automatic flash
set according to experimentation. For example, dancing
at the wedding, indoors, shutter at 1/2, f8, touch of flash to
stop the dancers... Has anybody on this list tried this with
M6? Any hints?

 These kind of situations are not so common to me to
justify another camera or camera system. It is also a
matter of principle...;-)

Regards,

Pasi Ohtonen