I only know about Second Life indirectly but since it's a 3D visual platform most of what one sees if one Googles "video upload Second Life" is 3D editor tutorials, tips, etc.
Particleillusion/PI is NOT 3D, it's 2D -- though it can give an illusion of 3D within film or video (which is maybe one reason "illusion" is part of its name :)
So to clarify, 2D and 3D = apples and oranges:
--- 2D = any film or video or still/photo, and so any PI effects used in any of these is also 2D. In all these cases you're dealing with a 2 dimensional = flat surface of pixels/bitmaps.
--- 3D is built with polygons and the like, not pixels. Anything that is a 3D platform such as Second Life needs 3D content for the content to work in 3D.
Of course on can render 3D work into 2D video/film/stills (i.e. I do it with my 3D program Vue). But one can't turn 2D into 3D --- at least not unless one is a major film or animation studio with very specialized, high-end tweaking software.
Maybe one can convert, tweak or integrate 2D video (i.e. in which PI effects are added) in at Second Life as a non-pro user, I simply do not know. The best way to find out is go to a Second Life forum and ask, check out their FAQ, send a Help/Customer Service question, Google around, etc.