Yes, a good explanation Watashiwateshdes.

Perversely, the newer your camera, the worse it will be at recording IR as the IR Blocking Filter built into all digital cameras has become more efficient.  Early DSLRs are much better.

You should still get a near IR image by using an IR filter as long as you give a long enough exposure - around 5 seconds or more for a 'normal' scene.  You will need to use B&W Mode and f8 or higher to get over the different focus setting for IR.

To answer your question, you really need a converted body which has had the blocking filter removed and a new visible light filter inserted between the mirror and the sensor so you can actually see the image in the viewfinder.  However, this is a costly option unless you are really serious about IR.

This is an interesting link: -

http://www.bythom.com/infrared.htm