Changing the system volume with a lirc enabled remote can be a pain in the arse if you don’t know what to look for. If you do, it’s quite simple:

There is a package called ‘pulseaudio-module-lirc’ (PulseAudio’s Wiki for module-lirc) that contains the volume control module for the PulseAudio sound server.

Install the package via yum

# yum install pulseaudio-module-lirc

and enable it

# echo "load-module module-lirc" >> /etc/pulse/default.pa

Here is a sample ~/.lircrc entry configured to forward signals to PulseAudio. Note that you may have to change the remote name and button names to match those in you /etc/lirc/lircd.conf.

begin
   remote = [your remote name]
   prog = pulseaudio
   config = volume-down
   button = [your vol_down button name]
   repeat = 0
end

begin
   remote =  [your remote name]
   prog = pulseaudio
   config = volume-up
   button = [your vol_up button name]
   repeat = 0
end

begin
   remote =  [your remote name]
   prog = pulseaudio
   config = mute-toggle
   button = [your mute button name]
end

Available configs include: volume-up, volume-down, mute, mute-toggle and reset.

Eventually, you have to reload PulseAudio:

# killall pulseaudio && pulseaudio -D

Update:

If you happen to have multiple PulseAudio sinks, you may want to modify /etc/pulse/default.pa like this

[...]
load-module module-lirc sink=[your sink name]
[...]

where you can get the sink name from PulseAudio manager ‘paman’ (flip to the ‘devices’ tab, and copy the name of the sink that you want the lirc module to control).