Officially speaking, there is no DIMES version for mac. Or, more precisely, there is no Mac version that has been developed for Mac OS X. There are plans currently to bring back support for Mac, but they are fraught with technical difficulties (we do not own a mac, and we have no one capable of cross-compiling the C code of our network stack for the mac)
I can offer you three courses of action that may work, from the lighter to the more intense:
1. Try the Linux version of Agent 0.5.5.3. Mac OS X is based on FreeBSD Linux, and so the linux version *may* work on it (we've never tried it)
2. Try to manually install the Linux version of Agent 0.5.5.1, which comes as a tarball from our site. Again, no guaranties that this would work. But at least if it doesn't you'll know the problem is with the Agent itself, not the installer.
3. If you are technologically savvy, you can always try to rebuild the thing from scratch on your own machine. We'd be happy to supply you with all the source code (Java and C), and if you manage it, we will forever immortalize your name on our site (assuming you donate the work back to us) BTW, this offer is open to any and all who read this
Sorry I can't offer you any better solutions.