Guide me on how to use my Mindstorm RCX kit on OS X Mavericks
I am currently maintaining my own fork of NQC for use on OpenBSD and OS X. As you have discovered, the recent compiler changes on OS X broke NQC in many places. Not to mention that the USB tower integration was pretty outdated. If you can compile it, it should work better than the ports version.

AFAIK, I am now the de facto maintainer for  NQC. (And may Crom have mercy on my soul, etc.)

Also, If you can find the right firmware (available around the usual places) you can update the RCX 1.0 to something like 2.x (or whatever the last release of the RCX firmware from LEGO is).

I make no promises this works at all, but I recall the last checked in version worked reasonably well with a serial tower on OpenBSD and a USB tower on OS X. A serial tower on OS X might work with the right incantations and USB/serial dongle.

If someone else other than me actually uses this, I might be prompted to cleanup my sandbox and commit my local repo (and fix bugs others find annoying.)