Programming RCX in 10.9 environment
For the RCX devices, if you want to use the RIS or RoboLab software on OS X, your best solution is to see if a VM image running Windows gives you what you want.

The main problem will be accessing IR Tower: the Mac doesn't have a COM port without a serial dongle (which could be had for cheap, but they can be a pain to use). And a USB Tower (if you have them) may not work in a virtualized environment. You would have to experiment.

Alternatively, you can use something like NQC or LeJOS for the RCX 1.0/1.5/2.x devices (any RCS 1.0 device will accept the latest 2.x firmware) on OS X. This is, of course, very command-line oriented.

Perhaps the latter solution could be reserved for the more advanced coders in the group.

I see that there is already an answer that enumerates some of the places you might be able to find RIS 2.0.