The original 568 spec allowed for this, except they wanted you to use an adaptor to pull out the blue/white and brown/white pairs. The idea was that the integrity of the cable remained intact all the way to the jack. What you plugged into the jack was your business.
10BaseT ran on pins 1,2,3,&6 (wh/or, wh/gn) - but that's a maximum of 10mbs. I don't believe you can push 100 mbs through on 2 pair, but you might.....
You also might be able to if you used the white/brown for voice- but all this depends on using older equipment.
The main point, as everyone has been saying, is that it's not recommended. It will certainly work. And if you were stuck - well, then the answer is maybe. At least for a short term solution.
For yourself - do what you want. A lot of residential will never run Internet much faster then 10 mbs anyway.
Sam
