You could host it on another site as a slide show, and then provide a link in a post on here.
I am not sure if Photobucket has a slide show option.
If you wanted to post individual PPT slides on here, then you can convert then to JPEG of GIF format first.
This is easy to do, open in PPT and save as JPEG or GIF, and select to save the whole presentation.
You would then need to uplaod the slides on here individually.