Set Task User Type with URL Hack

Question

I am working on creating a custom button that creates a task that has been prepopulated using url hacking. I've gotten almost all of my fields to work, but I am stuck on how to get the "Assigned To" field to change from the "User" type to the "Customer Portal User" type (see pictures below for reference).

From this:

To this:

My current URL code is as follows:

https://na88.salesforce.com/00T/e?
&tsk1={!Matriculation__c.Student__c}
&tsk1_lkid={!Matriculation__c.Student_User_ID__c}
&tsk2={!Matriculation__c.Student__c}
&tsk3_mlktp=a05
&tsk3={!Matriculation__c.Name}
&00Ni000000HXWGN="Finance"
&00Ni000000HXWGU=1

How can I set to "Assigned to" picklist value to "Customer Portal User"?

Answer 1

Modify your tsk1_mlktp value to be &tsk1_mlktp=CustomerSuccessUserLookup.

You can find this using the developer tools in Chrome. If you right click the <select> and click Inspect Element, you can view the children <option>'s and see what value corresponds with the label you want selected.