the only way that i can do is just
SelectionRange = xlWorkSheet.Range("A5:k5")
SelectionRange2 = xlWorkSheet.Range("A10:k10")
UnionRange = xlApp.Union(SelectionRange, SelectionRange2)
UnionRange.BorderAround(Excel.XlLineStyle.xlContinuous, Excel.XlBorderWeight.xlMedium, Excel.XlColorIndex.xlColorIndexAutomatic, Excel.XlColorIndex.xlColorIndexAutomatic)
anything easier than this...