This is the easiest way to do this. Not exactly the best way, because you need to repeat this process for all styles. The best way would be to create a cPanel Plug-in that redirected to your help desk when clicked. However, knowing that most web hosting providers only let their users use maybe 1 or 2 styles of the X3 theme anyway - here's the easy way to do this

:
1. Login to your cPanel interface using a Reseller Account's user/pass
2. Click on "Branding Editor" in the Preferences block
3. Below the style you wish to edit, click "Edit This Style"
4. Click "Add Interface Elements"
5. For "Select A Type:" select
Image
6. For "Select Image Category:" select
Icon
7. For "Create a Filename:" type a filename for your button, example:
myTech
8. For "Create a Description:" describe the button's use
9. For "Select Image Type:" select
Image
10. Height and Width is the height/width of the image.
11. Description is the text that appears below your icon
12. Ignore the Feature and If fields
13. For "URL:" enter the URL to link to (ex: the URL of your support desk)
14. For "Group:" enter the name of a group to place the icon in. Groups bundled with the X3 theme are: pref, mail, files, logs, sec, domains, db, software and advanced. If for some reason you already have created your own group, you can use that name as well.
15. For "Item Order:" place where you want your icon to be on the list (low numbers being near the beginning, high numbers like 999 meaning at the end).
16. Click "Add"
17. Click "Back to Branding Editor"
18. Click "Edit This Style" for the style you were editing
19. Click "Edit Icons"
20. You will now be able to upload your own icon. Scroll down to your icon (note the filename and Description will be displayed here), next to it is a browse button to upload an image. Browse for your image.
21. Click "Upload Images" at the bottom of the page
22. Repeat steps 3 through 21 for other styles of the X3 theme if you desire.