You'll need a device that converts an analog video/audio signal from your 8mm camcorder to a DV stream (Digital Video).
THe Dazzle Hollywood Bridge and tne Formac Studio DV are two such devices.
Also, if you're in the market for a new DV cvamcorder, many of them will act as an analog-digital "passthrough" device and function the same as the Dazzle and formac devices mentioned above.
I've got a Sony TRV25 than I have used as a converter/pass-through device to transfer a bunch of old Hi-8mm analog tapes to DV on my Mac.
- Tim