I suppose you mean runtime programming. The best way it to use MPC5700 C55FG Flash Standard Software Driver that is available on our website:
https://www.nxp.com/downloads/en/device-drivers/C55_JDP_SSD.exe

Example code you will find in its installation directory.
Also I could point out following example showing simple programming without using of SSD drivers. Even though it has been written for other devices, but the principle is similar:
Example MPC5643L Flash_program_simple CW210
https://community.nxp.com/docs/DOC-329440