Here's a example how to create an AppV Program in VB.Net
Set objNewProgram = oWMIService.Get("SMS_Program").SpawnInstance_()
objNewProgram.ProgramName = "[Virtual application]"
objNewProgram.PackageID = strPackageID
If you want to create a Task Sequence which installs a AppV package you've also to define this string as the program name.
Set objTSAction = connection.Get("SMS_TaskSequence_InstallSoftwareAction").SpawnInstance_