ORE is not supported on Macs. In fact we have never even tried running it on Macs. If you are just hacking around you can try building all supporting packages (DBI, ROracle, png) from source. Some of ROracle users were able to build ROracle on Macs so this might work.
I had good experience with similar projects in the past on MacOSX, so I thought I give this a shot. It actually also looked quite good in the beginning since a bunch of those R libraries load just fine.
I will see wether I get the relevant libs compiled from source. If you have any references to the attempts of compiling ROracle on MacOSX I would appreciate it.