I installed it the other day also... it is working very fine with Plus!....
I didn't experience any kind of problem........
I closed down msn messenger completely, killed the plus process, and uninstalled the ink redistributables. After that I installed InfoPen Pro...... (so I left the handwriting plugin installed; on startup it wouldn't work of course because the ink redists weren't installed anymore, but that doesn't matter. The point is, InfoPen Pro worked fine (together with Plus!) without any glitch....)
Helpfile for InfoPen Pro:
(this is found within the installation package, but if you want to know what it can do first, before installing, here it is)
http://members.lycos.nl/cookierevised/msn/handwriting/InfoPenMSN.chm
Screenshot of its "drawing" features:
http://members.lycos.nl/cookierevised/msn/handwri...PenPro_drawing.png
Screenshot of its "history" feature:
http://members.lycos.nl/cookierevised/msn/handwri...PenPro_history.png
(copy/paste links to new browser window)
EDIT: There is a known conflict between InfoPen Pro and the StuffPlug-NG plugin.