I'm trying to do this too so if i want to send down key is it like this
flirc_util send_ir_raw 1,4900,4900,840,1680,840,1680,840,1680,840,840,840,1680,840,1680,840,1680,840,6580,840,840,840,1680,840,840,1680,840,840,840,840,840,840,840,840,840,840,840,840,1680,840
Best regards
Aaru