The best free audio tool I have found is called 'Audacity'. Google for it, and you should have no trouble combining the wav's. You'll need to drop the finished file into the 'DropMOHAudioFilesHere' directory so the MOH Audio translator can convert it to the proper codec & set it up as an MOH source. You should also note that large files like this significantly increase the size of your CCM backups, as the backup utility includes all the MOH files as part of the backup image.
Also, you'll need to make this a multicast audio source. If you do it Unicast, your callers will hear the beginning of the file play each time they are placed on hold. I can't verify that Multicast won't do the same thing, as I haven't yet done a multicast source, but the Unicast definitely won't do what you want.
As one other poster noted, you can use the 'fixed audio source' option. I'm using Soundblaster USB audio adapters (SB MP3+) with my CCMs for the fixed audio. One problem I'm having is that the IP Voice Media Streaming App service freaks out on a daily basis and stops encoding the audio. Callers then hear silence until I reset the service. I suspect that this is partly because I'm not using Multicast (I have reasons for that). With Unicast, unless you have a dedicated MOH server, you are limited to 30 MOH connections per server. If it gets above that, callers will only hear a beep. So, I'd definitely go with the fixed audio source and make it multicast if your network permits, just beware that you may find it dies like mine does.
