Sen document ID from workflow to vault extension method


I have created new vault extension method:

[VaultExtensionMethod("MyVaultExtensionMethod", RequiredVaultAccess = MFVaultAccess.MFVaultAccessNone)]
private string MyVaultExtensionMethod(EventHandlerEnvironment env)

string docName = env.Input;


And I am calling that method from WF with VBScript:

Dim szDocName
szDocName = PropertyValues.SearchForProperty(0).TypedValue.DisplayValue

Dim strOutput
strOutput = Vault.ExtensionMethodOperations.ExecuteVaultExtensionMethod("MyVaultExtensionMethod", szDocName)

And that works great, I can read document name.

How do I pass Document ID to that method (instead document name) from VBScript? 

How can I send both (ID and name)?