You can do basic 3D text in PI X3, using one of the 3D object mode selections in the Text Tool's toolbar. From there, you can do some manipulation, such as stretching, moving, resizing, etc., using other tools within PI. You may find some of the Text libraries and Text/Path Effects galleries in the Easy Palette to be helpful.
A quick Google search indicates that there are tutorials on the web for this, and a glance through a few of them shows me that their explanations are far better than anything I could write. Some of the tutorials I found don't go much beyond the basics, but others may be more useful. Three that may be particularly applicable are http://www.emeraldangelzone.com/dlamarche/text_effects/3d_text/3d_text.htm
, and http://www.creationsbydawn.net/pi/tutorials/3-dlettertut.html
For more advanced uses, I have previously used Xara 3D for producing titles and the like. The result can then be brought into PI, so that you can incorporate the 3D text into your work. I don't currently have Xara 3D installed, so I can't give you more details. However, Xara currently offers a free online 3D Heading Maker, at http://www.xara.com/us/3d-heading-maker/
. You can save your graphic as a .PNG file to your computer. As you would expect, the free online applet is somewhat limited.
I readily admit that I am no expert in creating 3D text in PI. Maybe others on this board can offer the benefit of their experience.