If I understand correctly, these are checkboxes, so yes, you'll have to deal with if/else or select case (the second one is faster, but for my part, never had any problems with if/else).
After all, it all depends on what you want to do exactly (checking the boxes checked, incompatibility of choice...)
I prefer Cyril.f, for my use of a Select Case (Equivalent of a Switch in other languages, such as PHP, Java, etc)
Here is a processing example code (I put a full macro for the example as an attached file):
Private Sub BtValid_Click() 'We do a treatment on the value Select Case ComboBox.Value Box "U1": MsgBox "I'm doing a treatment on U1" Box "U2": MsgBox "I'm Displaying U2" Box "U3": MsgBox "I'm U3" Case Else MsgBox "Default Processing on Value" & ComboBox.Value End Select End Sub
Edit: Note that I only do the processing on the U1, U2 and U3 values, all the other values will take the "Case Else".