Sure, it can be done. I installed that head unit in my 08 not long ago. This sticky thread is a great place to start:
I prefer Sonic Electronix, but this same stuff can be bought at Crutchfield:
Since you have JBL system, you will need this harness:
Get this to retain steering wheel controls (no programming involved):
This is not necessary, but makes simple work of wiring the above steering wheel interface. It has been out of stock everywhere lately, but you can find it on eBay:
You can buy an add-on GPS unit for the avhp4300dvd:
There are two dash kits that will work. People seem to be divided on which is best. I think they are both merely adequate, but favor the Schosche kit because it seems to fit better:
Metra also makes a kit that is textured like the stock dash piece:
Grab one of these if you plan to use an iPhone or iPod:
Grab one of these relays for your bypass:
And finally, look here for instructions on how to wire the bypass relay:
Unless you plan to solder, you will also need some crimp connectors and a crimper. Overall, it is pretty straightforward to install an aftermarket head unit.
When I installed this head unit, I spent quite a bit of time fussing with the placement. In the end, I'm very happy with the way it looks in the Tacoma. I think it looks better than the stock head unit.
One other thing worth mentioning -- if you happen to have an iPhone, you can use MotionX for GPS instead of the expensive GPS module.