1. You shall add Mode with meaningful value and follow DisplayPort Alt Mode. If Mode with 0x0405 and 0x0805 is what you are going to support. You could add them into configuration table with Ez-PD configuration Utility.
2. How to do it? You just need click the button + on the right top of SVID tap, the new mode will be added below Mode 0, you could edit it as per your SPEC. And the generated config table, update it into firmware project file config.c.
3. All of firmware example code can be availed if you download CCGx SDK from link: http://www.cypress.com/documentation/software-and-drivers/ez-pd-software-development-kit?source=search&cat=software_tools