anyone can advice me....i like to use simplink
my devices:

astro decoder (normal not HD)
LG 42LF20FR LCD tv
LG HT554TM-A2 Home Theater Systems
sony ps3

how i want to have all the sound out from my HT?
currently i install :
astro -> lcd tv
ps3 -> lcd tv hdmi
ht -> lcd tv hdmi

i want to play ps3 and have the sound on HT
i want to watch astro and have the sound on HT

please advice