It turns out that a combination of the "PNP OS" setting (must be NO) in the BIOS and the "exclude irq" settings in the /etc/pcmcia/config.opts file were the culprets. Here is my final discoveries -- thaks to Jeremy at Sony engineering (friends in low places....) for pointers:
Make sure that /etc/sysconfig/pcmcia is set to include the following:
And add the folloing to /etc/pcmcia/config.opts:
Unfortunately, cardmgr doesn't seem to work if you just pop cards, but by simply stopping pcmcia, swap cards, and starting pcmcia, all is well.
As an additional note - the commercial OSS drivers support the Yamaha sound chip, but (again) are effected by the "PNP OS" setting in the BIOS -- make sure that it is set to NO!