I figured out how to use VBA and set up a Module in Access as follows:
Option Explicit

  Function CountElements(ByVal S) As Integer
  ' Counts the words in a string that are separated by semi-colons.

  Dim WC As Integer, Pos As Integer
     If VarType(S) > 9 Or Len(S) = 0 Then
       CountElements = 0
       Exit Function
     End If
     WC = 1
     Pos = InStr(S, ";")
     Do While Pos > 0
       WC = WC + 1
       Pos = InStr(Pos + 1, S, ";")
     Loop
     CountElements = WC
  End Function

  Function GetWord(ByVal S, Indx As Integer)
  ' Returns the nth word in a specific field.

  Dim WC As Integer, Count As Integer, SPos As Integer, EPos As Integer
     WC = CountElements(S)
     If Indx < 1 Or Indx > WC Then
       GetWord = Null
       Exit Function
     End If
     Count = 1
     SPos = 1
     For Count = 2 To Indx
       SPos = InStr(SPos, S, ";") + 1
     Next Count
     EPos = InStr(SPos, S, ";") - 1
     If EPos <= 0 Then EPos = Len(S)
     GetWord = Trim(Mid(S, SPos, EPos - SPos + 1))
  End Function