I think i get what you mean you want sResult to display what the command argument said but with text added to it. Correct me if i am wrong.
code:
Public Function ParseCommand(ByVal sCommand As String, ByVal sCommandArg As String, ByVal oConversationWnd As Object, ByRef sResult As String) As Boolean
If (StrComp(LCase(sCommand), "/xtest", vbTextCompare) = 0) Then
If sCommandArg = "%hello" then
sResult = "You just said to this plug-in: " & Replace(sCommandArg,"%","")
End if
End if
ParseCommand = True
Exit Function
End Function
The Replace bit just gets rid of the percent. If you want it there you could just say:
sResult = "You just said to this plug-in: " & sCommandArg