Its been a while, so there is a possibility that Im getting something a little wrong on this, but From what I recall, you have to first install Apache VS Havoc. Then run it once so that it... I honestly don't remember what it is that it does the first time you run it, but It does something, so do it. After it does its thing you need to install Comanche VS Hokum. It has to be installed in the same directory (or folder, or whatever term is in use these days) in order for the games to properly be linked. That means that you cannot just use the default directory for both games. If you have done it correctly the title screen of Comanche vs Hokum should say "Apache Havoc Installed" in the upper right side. After that is when you can install the mod.

Hello.
EECH+allmods does automatically detect EEAH if it is installed. According to EECH Central, EEAH is only needed for working gauges in the Havoc cockpit. Allmods v1.16 already has the EEAH campaigns + Apache + Havoc. From messing around, I didn't notice any difference in the Havoc cockpit with or without EEAH installed. As such, I uninstalled EEAH.

Thanks all.