This is a quick and dirty tutorial for calling a CTools/Panels 3 custom handler from code. It works for handlers for the system pages, such as the user page override. Calling custom/panels pages from code is different. Make sure you replace all instances of MODULE_NAME with your module's name.
Step 1: Create a file named MODULE_NAME.delegator_default.inc and put it somewhere in your module's directory.
Step 2: Paste in the following code.