As a concept (ie I didn't test this because I don't know where you got your Checkboxes from) try these macros
Code:
Public Sub CheckBox1_Click()
ShowHideLayer "To Be Form", CheckBox1.Value
End Sub
Public Sub CheckBox2_Click()
ShowHideLayer "SHC As Is Form", CheckBox2.Value
End Sub
Public Sub CheckBox3_Click()
ShowHideLayer "Works As Is Form", CheckBox3.Value
End Sub
Public Sub ShowHideLayer(sLayerName As String, bShow As Boolean)
Dim aPage As Visio.Page, aLayer As Visio.Layer, aCell As Visio.Cell
For Each aPage In ActiveDocument.Pages
For Each aLayer In aPage.Layers
If aLayer.Name = sLayerName Then
Set aCell = aLayer.CellsC(visLayerVisible)
aCell.Formula = bShow
End If
Next aLayer
Next aPage
End Sub