First of all, if you want just open Excel, then you need two lines:
ExcelObject=createObject("Excel.Application")
ExcelObject.Visible = .t.

Now to your question:

>Excel = createObject("ExObj")
>Excel.Show()
READ EVENTS

>DEFINE Class ExObj as custom

>ExcelObject = null

>Function init
this.ExcelObject=createObject("Excel.Application")
this.ExcelObject.Visible = .F.

>Function show
this.ExcelObject.visible = .T.

>ENDDEFINE

You will need to add destroy procedure with clear events.

Still I would not recommend to use your code. Use plain Excel Automation instead.