You would use some ALSA or OSS mixer to set the appropriate volume.

macabro22@GIR:~/download/som/alsa-driver-1.0.15$ modprobe snd-hda-intel
macabro22@GIR:~/download/som/alsa-driver-1.0.15$ 
macabro22@GIR:~/download/som/alsa-driver-1.0.15$ lsmod | grep snd
snd_hda_intel         363808  0 
snd_pcm_oss            58496  0 
snd_mixer_oss          20608  1 snd_pcm_oss
snd_pcm               102536  2 snd_hda_intel,snd_pcm_oss
snd_page_alloc         13200  2 snd_hda_intel,snd_pcm
snd_seq_dummy           5764  0 
snd_seq_oss            39296  0 
snd_seq_midi           12416  0 
snd_rawmidi            31616  1 snd_seq_midi
snd_seq_midi_event     10112  2 snd_seq_sdummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq
snd                    78904  13 snd_hda_intel,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_page_alloc,snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq_midi_event,snd_seq,snd_timer,snd_seq_device
soundcore              10272  1 snd
macabro22@GIR:~/download/som/alsa-driver-1.0.15$ 
macabro22@GIR:~/download/som/alsa-driver-1.0.15$