Easy method, but takes up wiki space.
Click on "Add files" link at the bottom of your wiki page.
Select and upload the PPT file
Google Presentations does not take up wiki space and also allows editing, collaborating, and commenting.
Follow the instructions below or visit the this page at the NIEfolio Help Site.
Visit http://drive.google.com
Click on "Create" and select "Presentation"
Select a blank template
In the new presentation tool bar, click File -> Import slides... -> Upload and select your PPT file
Wait for the PPT file to be converted to a Google Presentation
Return to your wiki page in Edit mode
Click the point where you wish to insert the Google Presentation
Click on Insert -> Presentation -> Select your Google Presentation
Change the options presented to you if you wish
Save the changes to your wiki page