Hello,
If you mean being able to scribble or draw with your Wacom tablet and have
that remain as paths or lines on your slide that you can later save or edit,
you can do this in either Normal view or Slide Show mode. However, the
process works a little differently.
In Normal mode, you can use the Scribble tool, located under the Lines and
Connectors icon in the Drawing toolbar, to draw lines as you like. If you
can't see the Drawing toolbar, select it under the View - Toolbars menu.
In Slide Show mode, if you right-click on the page, there's an option to
switch to the Pen tool, which you can use to mark up the slide. However,
these pen marks will NOT be saved (at least, not in the Office 2008 for Mac,
unfortunately). If you want to save an image of the markup you made in this
mode for that slide, do a Shift-Command-3, and the current screen image will
be saved as a PNG image to your desktop.
Remember that PowerPoint and Photoshop are different animals...
PowerPoint is a slideshow authoring program with a decided leaning towards
objects and vector graphics. Photoshop is a bitmap editor that happens to
have some vector graphic functions, but at its heart, it's a bitmap editor.
Use one to complement the other, and you'll be really rolling.
Jeff