There are basically three ways to DIY this -
1 - purchase a DVD recorder, perhaps one that has both a VHS deck and a DVD recorder in the same unit. This is the easiest way to dub your VHS tapes direct to DVDs. Quick & easy, and some of these recorders are under $99. No editing, however.
2 - get an analog-digital converter like the
Canopus ADVC-110. You would connect your VHS deck outputs to the converter inputs; then connect the converter to your Mac via FireWire. Then capture the video as you would from a miniDV camcorder. Runs about $230. This is my recommended way to convert VHS video for editing.
3 - use a miniDV camcorder as a converter. You will need a camcorder that supports analog-digital passthrough (most do). Connections & use would be the same as for the Canopus ADVC-110 above.