Sorry for the self-follow-up, but I re-read your other
question.
Is this Pegasus product hardware or software? Both?
If it just "replaces" the mouse like a Wacom external
digitizer does, then you should be OK to use it as
a "pen" in OneNote. (The oft-repeated caveat that
anything that you draw with it will be treated as a
picture and cannot be converted to text or
indexed/searched).
If it somehow uses its own datatype/API to store pen
stroke data then you won't be able to use it at all with
OneNote unless there's a capability to have Pegasus
convert the handwriting to text and *then* place the text
at the insertion point (similar to the way that the TIP
works in a Tablet PC.