Text-to-Columns can only accept a single character as the 'other' delimiter but Split can divide on any number of characters as the delimiter¹. Simply write your own version of Text-to-Columns.
Option Explicit
Sub myT2C()
Dim vals As Variant, tmp As Variant, i As Long, j As Long, mx As Long
With Worksheets("sheet8")
vals = .Range(.Cells(2, "A"), .Cells(.Rows.Count, "A").End(xlUp)).Value2
For i = LBound(vals, 1) To UBound(vals, 1)
tmp = Split(vals(i, 1), "//")
mx = Application.Max(mx, UBound(tmp) + 1)
ReDim Preserve vals(LBound(vals, 1) To UBound(vals, 1), 1 To mx)
For j = LBound(tmp) To UBound(tmp)
vals(i, j + 1) = tmp(j)
Next j
Next i
.Cells(2, "A").Resize(UBound(vals, 1), UBound(vals, 2)) = vals
End With
End Sub
¹ There is probably a limit that I'm unaware of; perhaps 255 characters.