You'll need the serial flashing cable from Gene, an FTDI-chipped USB-serial adapter (the one sold by Eric Rechlin at hpcalc.org works great for me), up-to-date Mac drivers for the adapter (from FTDIchip.com) and flashing software so you can keep the calc updated. I cannot get Pascal's Qt flash software for Mac to work for me, and frankly haven't had time to troubleshoot it with him. I do my flashing with MySamba under Windows XP, virtualized on my Macs with VMWare Fusion.
Pascal's Qt emulator for Mac works superbly and I use it to send RAM contents back and forth between calc and computer using the commands RECV, SENDA, SENDP, etc. This has worked flawlessly, which makes it even more mystifying why I can't get the flash tool to work. Keep in mind that the Qt emulators are a separate but related project of Pascal's. They do NOT get built every time Marcus, Pauli, Walter, etc., do an integration build of the ROMs and the Windows emulator. So the Mac emulator is a bit out of sync--now in revision 2783, whereas the calc firmware is up to 2830, with more builds due any day now.
If you really want to get serious about this calc on the Mac you are going to want to learn about the various build scripts which can take text listings of code and turn them into programs and libraries that can be sent to the calc over the serial cable. These are Perl scripts that run in Terminal.
I don't know if this saves you money, but it may be worth your while just to get a 30b at the best price you can find it, the cable and adapter, and overlays from Eric, and flash it yourself. You're going to to need all of this stuff anyway if you want to keep abreast of the ongoing development. And it isn't expensive at all.
I am concerned that you are running OSX Tiger, which is ancient in Mac terms. I have no idea if Pascal's emulator, flash tool (if you can get it to work), or the most recent up-to-date FTDI drivers are compatible with 10.4. Something to put to the group.
Hope this helps.
I really encourage any HP calc enthusiast to jump on this bandwagon. The calculator has all of the coveted power of the legendary 42S combined with speed and I/O abilities. Plus, it comes with its own dedicated team of HP lovers and enthusiasts who just keep chugging--free of charge. Think about it--you find a bug, one of the guys fixes it within hours and you get new firmware to flash. My barely-touched 15C LE still has the PSE bug. The WP34S is a wet dream--a powerful keystroke programmable with a personal touch. It is by us and for us. And I spent a lot less on this than I have on collectibles I just had to have in days of yore that now I barely touch.
Edited: 21 Apr 2012, 6:37 a.m. after one or more responses were posted