How do I dynamically filter input values?

Let me start out by saying I'm a sysadmin with some coding experience, but I would never call myself a developer.

I have a single workflow for provisioning VMs in multiple physical datacenters.

Each datacenter has it's own vCenter with multiple ESX Clusters, thus one "cloud" per datacenter

Each Cloud has multiple vDCs

Each Cloud has multiple vmware templates which are set up as Catalog Items

My current workflow prompts the user for the desired machine name, the cloud [vmwareCloudNamesList], the vdc [vDC], and the catalog item [Custom LOV] (along with some system specs)

How do I limit the usrVDC and usrCatalog items based on the usrCloud selection? The Cisco UCS Director Custom Workflow Task Management Guide indicates that this is possible, but does not go in to detail.

I sent this to you the other day, but for the benefit of anyone else looking, here's a good read through on this:

UCSD List of Value (LOV) Tutorial (Multi Select Check Box LOV from CSV file)