Right, you’ll need at least version 1.2 for plugin compatibility. Can you download current version 1.2.4, diff your customizations and reintegrate them into it? There are a few nice additions and fixes since the version you must be working with, so it’s probably worthwhile.
Generally the version can be found in the OpenEars.xcodeproj source files in the comments at the top, and in a file called Version.txt in the root of the OpenEars directory. Since 1.2 it is also shown in the manual and in OpenEarsLogging.