Here's a quick tutorial...

(1) Create your text as black on a white background (I used paint for this one), and save as a bmp.

(2) Click in the fist spare channel for bump map.

(2a) Click the P (next to 4 on the diagram) to change the texture into a picture.

(3) Import the text picture into the second (value) channel.

(4) Click the downwards triangle at the bottom of the texture box, and choose object front.

(5) Set the bump height value to -100 (or whatever you want).

(6) Render

Come visit us at RenderGods.

Ignore the shooty dog thing.