An AC-DC transformer would be necessary, no more than 12.5-13.5V / 3000-5000 mA (3-5A)... Any thermal or electronic flasher from a parts store or salvage yard vehicle should do. I would recommend swapping bulbs for LED versions, as they will not require as much current (hence brighter with less current) and work better with lower-output transformers.
You might also consider integrating a small rechargeable 12-14V battery like those used in power tools, RC cars and the like into the power feed. This will act as a buffer so the AC adapter is simply charging the battery, not bearing the full load.
Wiring is easy. It's all 12V (+) and ground (-). Best part is, for this application, aside from the flasher and any battery buffer, polarity is irrelevant as long as you don't have a 12V and ground crossed. Light bulbs generally work just fine regardless of polarity.
"CHEESE WAGON" <email@example.com> Suggested reading: (5 threads)