Based on this process:

Alternative procedure to copy a formula down for the range
D22:D125:

1 Select the cell with the formula (D22)
2 In the Name box, change D22 to D22:D125
3 Press Enter to select
4 Press Ctrl-D (that's the Ctrl key and D together)

Here's what I've got so far:

Private Sub OK_Button_Click()
Application.ScreenUpdating = False

Dim i As Integer

Set UserRange = Range(DataFill.Start_Cell)

Range(DataFill.Start_Cell).Value = CInt(Beg_Val)
End_Val = CInt(End_Val)
Incr = CInt(Incr)
Range(DataFill.Start_Cell).Select
ActiveCell.Offset(1, 0).Select
ActiveCell.FormulaR1C1 = "=R[-1]C+" & Incr
Selection.Copy
i = (End_Val / Incr) - 1
ActiveCell.Offset(i, 0).Activate
Selection.FillDown

Unload DataFill

Application.ScreenUpdating = True

End Sub

I'm down to the point where I've selected and copied the
formula. Now I want to highlight the cells down, based on
the fomula for the variable "i" and then filldown the
formula.

I'm trying, and not having much luck by trying to
accomplish this using some variant of "offset".

Basically, what I want to do is:

User input:

Start_Cell
Beg_Val
End_Val
Incr

Where what happens from there is:

Goto the Start_Cell
Enter the Beg_Val
Drop down one Cell
Enter the formula = (One Cell Up) + Incr Value
Copy this Cell
Select, Highlight, or Activate Cells down based on an
offset of:

i = (End_Val / Incr) - 1

So, for:

Start_Cell = E5
Beg_Val = 3
End_Val = 30
Incr = 3

i = (30/3) - 1
i = (10) - 1
i = 9

(Based on the way I've got this setup so far, the end value
could be either -1 or -2 (i.e. (30/3) - 1 or (30/3) -2)
depending on what works best for this)

Would then drop down, highlight, select to E14
and copy or filldown the formula from E6 through to E14
creating the series:

3 - 30 in cells E5:E14 incremented by 3

So far, I'm not having much luck with this very last piece
of the puzzle.

Is this the best way to go about this? and
Is this the most optimal code to write?

Anyone?

Thanx.