One calendar to rule them all

I've been trying to locate a way to link my Datebk6 calendar on my Palm (a Treo 680) with some kind of .ical-compatible calendar on the PC so that I can have all my appointments, etc. wherever I am. I do use the Google Calendar since GMail is such an important hub for my work, so that's the one I'd like to work with.

Things I've tried so far:

• Airset - would work if I could use Palm Desktop 4.1.4. I can't I have to use 6.x because the Treo won't sync to the older version, otherwise Airset's cloud-based computer with built-in calendar app that syncs to .ical would be ideal.
• I found someone saying that the Yahoo calendar syncs to Palm Desktop, but again only the older 4.1.4 version
• I found software called DBA2CSV/Palm2Google, which looked ideal on first blush, but it's really a one-way thing for people migrating from a Palm platform to something that supports the .ical standard. The author replied to my query very rapidly though, so I can recommend it for the responsiveness of the author if you do want to migrate (although it does seem to really be a one-use tool and thus somewhat expensive)
• If I could get Palm Desktop to export my calendar data in .vcs format, the standard from Microsoft used for Outlook that .ics the .ical standard is mainly an evolution of, things would be better, but the option to export as .vcs is ghosted on my Palm Desktop - I wonder if it's because I don't have Outlook?
• Thunderbird 3 now has a new calendar extension called Lightning that can optionally understand .vcs files, so if I could translate my Datebk entries to .vcs, then into Lightning where they could be synced through .ical to Google Calendar that would tortuously solve the issue - after all, it's not like I'd need them to be so synced I'd need it OTA, I don't want OTA, just to sync with palm Desktop.

Dang! Since the Treo is dead tech, it seems that the only alternative to stay with some kind of PalmOS is to get a Palm Pre, but the cost is out of my budget for now, especially if bought on a contract. Gah