You can try a function like this:
Code:
Function ConcatRows(sce, WhichRows)
For Each rw In WhichRows
Z = Z & sce.Cells(rw).Value
Next rw
ConcatRows = Z
End Function
and use it in a worksheet thus:
=ConcatRows(A1:A15,D1:D4)
or:
=ConcatRows(A1:A15,{2,4,6,8})
No checks or bells and whistles.