OMiGA is open source now and available at github.
A previous and buggy version of OMiGA can be downloaded here. To run OMiGA, unpack the archive, change directory into omiga/ and type
java -jar omiga.jar <filename>
The benchmark instances are also available. They were run on an Intel Core i5 PC with 4 cores at 3.30GHz and about 3.8GB RAM, running openSuSE Linux 12.1. For benchmarking OMiGA was started with the following command line
java -Xms256m -Xmx2000m -jar omiga.jar <filename>