C# - way to programmatically advance Powerpoint slide show?

I'd like to be able to advance through a Powerpoint presentation by pressing buttons in a Windows form. Here's some code I've found from http://bytes.com/topic/c-sharp/answers/272940-open-powerpoint-presentation-c-window-form that opens a Powerpoint presentation slide show:

Microsoft.Office.Interop.PowerPoint.Application oPPT;
Microsoft.Office.Interop.PowerPoint.Presentations objPresSet;
Microsoft.Office.Interop.PowerPoint.Presentation objPres;

//the location of your powerpoint presentation
string strPres = @"filepath";

//Create an instance of PowerPoint.
oPPT = new Microsoft.Office.Interop.PowerPoint.ApplicationClass();

// Show PowerPoint to the user.
oPPT.Visible = Microsoft.Office.Core.MsoTriState.msoTrue;

objPresSet = oPPT.Presentations;

//open the presentation
objPres = objPresSet.Open(strPres, MsoTriState.msoFalse,
MsoTriState.msoTrue, MsoTriState.msoTrue);

objPres.SlideShowSettings.Run();

I haven't found any methods that can advance through the slides, however. Any ideas?

(Really what I'm trying to do is use the WiiRemote to advance the slides, for a student project).