I think you should consider to use the so called Asset Lifecycle Manager/Process Manager (same product with two different license types) or another workflow tool to achieve your goal.
I believe in some licensing models the Asset Lifecycle Manager (ALM) is included. The ALM is a tool, that can process web service calls from Service Desk and e.g. add new or update existing AD accounts. You just need to prepare a process, that will collect some data and send them to the ALM. There you can set up an additional process that will do the changes in AD.
So at first I'd recommend to ask your Ivanti Account Manager, if the license is included. Then I'd check the landing page of the ALM (Asset Lifecycle and Process Manager Frequently Asked Questions ). There are some processes included in the ALM database, maybe there are some you can use. There are some knowledge articles in the community, that will describe similar things (How To: Use LPM to Create a New Mailbox / AD Account with Powershell ). For configuring Web Services in Service Desk, check the help for Service Desk (Service Desk and Asset Manager help center ).
As an alternative, there are many workflow tools, that will do almost the same thing or even more than the ALM. But in most cases they are very expensive...
Let me know how you get along!