Switching the diodes in and out would work - you'd need to flick the switch and select left or right for hazard lights, but I can see three problems with that:
- it'd be even messier than wiring the flasher up for 4 ways
- the warning light wouldn't work during 4 ways
- the limited amount of spare space under the console (especially if you have a tach or clock) would make it impractical.
In the next couple of days (work permitting) I'll be doing a write up on how to make a very simple & cheap LED replacement globe for the turn signal warning light WITH the isolation diodes built into it. I'd recommend you do that, and the 4 way mod on my site. (You'll also be able to use that circuit to make "daylight visible" LED globes for the other warning lights by ignoring the diodes and selecting the appropriate coloured LED).
