Software Used: Audacity v2.0.2 with LAME Encoder to splice the audio together, GCFScape v1.8.3 to open the original Half-Life.gcf file and exract the WAV audio.
How the Process Went: I simply added the HEV's voice files in the order they originally played out in Half-Life '99 into the music track "Anomalous Materials", which was composed by Joel Nielsen of the BMS Team.
Why I Made This Addon: I just wanted to add a little bit of consistency between HL1/GS/S and BMS when it came to the HEV Voice.
Known Bug(s): Since the included music file will continue to play in-game until it comes to an end, the HEV will likewise continue talking if you pause the game. Also, due to this method of sound additions, there is a likely possibility that any NPC you talk to will end up stepping over the HEV's lines (as in, they both talk simultaneously). In this case, the NPC in question will be much more audible than the music (and thus forth the HEV voice).