ASP.NET WebParts are not the same thing as Sharepoint WebParts. You cannot use Sharepoint WebParts in mojoPortal.
ASP.NET WebParts came out in 2005 as part of .NET 2.0, I was excited about it at the time so I implemented support for ASP.NET WebParts in mojoPortal. But ASP.NET WebParts never caught on or became popular, there are no third party ASP.NET WebParts.
Hope it helps,