See if
this link works. If so, this should be all that you need to do the swap, outside of some custom work to mount the bags. You're looking at $2400 for the system best I can tell. No way I'd tackle this for the money/risk, but if you're set on it I'll provide as much info as I can.
In addition to the above, there are a couple other things you need to know. There are two switches in the center console. One adjusts the bags up/down, the other turns the system off. Also, the gauge cluster is different for models with the system. There are indicators for position and on/off. You'd need these to make it work properly.
One more thing. I'm not sure if your 4runner would be prewired for this or not. This may require a ton of custom wiring to get everything hooked up and functioning.
Even if you were able to get the components used for a reasonable price, it'll be a huge endeavor just trying to get it all hooked up. You'd be much cheaper and a lot better off if you'd get the Burtman lowering springs. I know they're over $500, but if that's the look you're going for then it's your best bet. Your only other option is to pick up a spare set of springs and start cutting. Not the way I'd go, but an option. With all the guys doing the FJ swap, you could probably get a full set of springs for the cost of shipping.