Update 9/28/12: Summary: I have Chirp 0.2.3 working in OSX 10.8.2 with my FT60s using an RT Systems cable. I was able to write to both radios on the first attempt with each. - No jiggling/pressure on the plug required. - The radios were left in memory mode vice VFO. - The cable is in a second-level USB hub vice plugged directly into my MacBook. - No incense was burned, no chicken entrails arranged. It worked just like a piece of modern electronic gear, imagine that.
A bit more detail: I looked at the suggestion to use a linux live CD. I'll follow up in a separate post on that, but googling around, it's complicated on a Mac; there's going to be a substantial learning curve. I thought about where I prefer to end up, which is programming my radios under OS X, vice learning exactly what's wrong with my two Prolific cables or their driver, and decided that my best course of action was to buy an FTDI-based cable. Valley Enterprises, recommended on the Chirp site, has one for $28. And for an unrelated application, I already have an FDTI driver installed that I know works.
But given my recent experience with 3rd-party cables, and this comment from Dan Smith : "For what it's worth, I have always had trouble with the FT-60 and aftermarket cables. ... other than the one from Yaesu... ". and see that for ~ $10 more, I can buy the one both HRO and Universal Radio are selling as FT60 accessories, which I assumed was the official Yaesu cable. [ Comes with Windows software I have no use for, but whatever ]. And my local HRO has it in stock, I can have it today...
So here's where I make a couple of mistakes, and then get very lucky: I somewhere thought I read that the official Yaesu cable uses FTDI. And I thought the ADMS-1J being sold for this by two major Ham retailers was the official Yaesu product.
Get the box home, plug it in, and it's clearly some funky RT systems proprietary interface (I can see that in the USB device tree), and I don't have a serial port, so it's neither Prolific nor FTDI.
So I'm wondering if HRO will take it back, the software is still sealed. But I googled for an RT systems Mac driver, and this was the first hit: http://www.rtsystemsinc.com/kb_results.asp?ID=9 Turns out RT systems isn't interested in porting their software to the Mac, but they've decided to provide a driver!
So I install it, and sonofagun, I've got a serial port named /dev/cu.usbserial-xxxxxxxx where the xxxxxxxx is the serial number for the RT device I see in the USB tree. Start up Chirp, plug in the radio, start a download, and wham, there it is. Spot checking the 100 new memories in my FT60, looks like it's all accurate.
So, I've got a working solution. I might try troubleshooting my Prolific cables, but that has lost a great deal of its urgency and interest... It's possible that RT Systems won't keep their driver up to date for OSX 10.9 or 10.10, but I should have a working solution for a couple of years at least. If I'm still alive and still care when I can't still at least boot to 10.8 from my external clone backup, I'll deal with it then.
FWIW, neither I nor my micrometer can see any significant physical difference between the 3.5mm 4-conductor radio plugs on the RT cable vice the Kawamall / eBay cables. I'm guessing the most likely issue is bad Prolific chips or the assembly/connections to them, then driver issues, with a probably pretty small chance it's a Chirp problem.
Thanks for all the support. I hope my experience will help someone else navigate this a little more surely.
-dan