On the page http://ko.infragistics.com/products/windows-forms/grid-excel-exporter/ all the way at the bottom next to "Additional Resources" there's a "Related Links" section. The link for "API Documentation" points to a non-existent page.
I eventually figured out I can go to http://help.infragistics.com/NetAdvantage/WinForms/
Hello Smercurio,
I would like to let you know that the links have been corrected and you could use them now freely as well.
Please feel free to let us know if you need any other assistance with this matter.