Aaron,

The macro below will do that - assumes that your output table starts in cell A1 and is contiguous.
It will save the files in the folder where the workbook with the macro is stored.  If it starts
elsewhere, change the line

With Range("A1").CurrentRegion

to reflect the address of the upper left cell.

HTH,
Bernie
MS Excel MVP

Sub ExportTo90LineCSV()

Dim fName As String
Dim WholeLine As String
Dim FNum As Integer
Dim RowNdx As Long
Dim ColNdx As Integer
Dim StartRow As Long
Dim EndRow As Long
Dim StartCol As Integer
Dim EndCol As Integer
Dim I As Integer
Dim FCount As Integer
Dim strPOnum1 As String

strPOnum1 = "Whatever"

fName = ThisWorkbook.Path & "\" & strPOnum1 & " " & Format(Now, "mmddyy")

Application.ScreenUpdating = False
On Error GoTo EndMacro:
FNum = FreeFile

With Range("A1").CurrentRegion
   StartRow = .Cells(1).Row
   StartCol = .Cells(1).Column
   EndRow = .Cells(.Cells.Count).Row
   EndCol = .Cells(.Cells.Count).Column
End With

For I = StartRow To EndRow Step 90
FCount = FCount + 1
Open fName & " " & FCount For Output Access Write As #FNum

For RowNdx = I To I + 89
   WholeLine = ""
   For ColNdx = StartCol To EndCol
       If WholeLine = "" Then
           WholeLine = Cells(RowNdx, ColNdx).Text
       Else
           WholeLine = WholeLine & "," & Cells(RowNdx, ColNdx).Text
       End If
   Next ColNdx
   Print #FNum, WholeLine
Next RowNdx
Close #FNum

Next I

EndMacro:
On Error GoTo 0
Application.ScreenUpdating = True

End Sub