Doesn't the GC have a modem ?
You can connect your DC to your PC using its modem. It's quite simple since DC's OS is a Win CE OS, so it's quite easy to communicate with it and use it as a GD reader. But I don't know what runs on DC...
And I don't think any drive would read GC disks since they aren't like CDs : more data and they're compressed. Maybe a DVD reader, someday...
*Megalexxx's dreaming"