I have spent a lot of time trying to find out the answer to that question....the result I have found (through Internet resources and measurements I have done personally) is that the 4Runner's hood doesn't fit the Tacoma...you'll notice that the grills are different between a 4Runner and any year Tacoma. Also, one of the vehicles hood is about an inch longer than the other (can't remember which, but I measured myself).
I wanted to get one in the hope that my supercharger would have some more room and not scrape against the hood like it does now (plus I like the looks)...I was referred to a site that makes custom hoods for Tacomas:
http://www.toyotafiberglass.com
You might want to check out what they've got...though I have heard fiberglass has some problems (only heard, though; I'm not sure what the real deal is). Also, I think they only make cowl induction hoods, and not scoops....
I do know that at least one person on
www.TacomaTerritory.com had a custom hood done with a scoop that looks just like the 4Runner's....if you haven't already, you might want to ask around there...
Anyway, hope that helps,
Mike