This is certainly possible with the portal customisation feature on the Estate plan. Here's a snippet that you can use to place a tooltip next to a field on the new ticket page layout (Admin -> Portals -> Customise portal -> Portal pages -> New ticket page section):
<a target="_blank" href="#" id="test" title="Insert your text here"><img src="https://shots.jotform.com/kade/Screenshots/blue_question_mark.png" height="13px"/></a>
Hello! I would like to accomplish something similar and tried your code, as is, however, the tooltip is showing up at the top right, not at the field level. Here is what I mean:
Do I need a JQuery library or something? If so, how/where do I add it?
In the same idea, can one add just a text comment with a link, just before the field, to a solution within the Helpdesk? For instance, we would like to let customers select their ticket priority, upon ticket creation, but we would like to give them a link to a solution that details the criteria that define each priority level, so that they do not set all tickets to Urgent....