With some help from the beta forum i found a way to enable flac playback for the PS3. This is for twonky version 5 beta 1.
Edit flac-wav.desc in /cgi-bin and input this :
exec: flac --decode --force-raw-format --sign=signed --endian=big --silent $infile -o $outfile
from=audio/x-flac
to=audio/L16
dlnaprofile=LPCM
asynchronous
Also remember you need flac.exe in cgi-bin.
Thanks to the people in the beta forum(dont remember their names atm).
Regards
The1n