Hi Anusha,
We don't provide source code for the LPC-Link2 firmware that is developed by NXP for LPCXpresso/MCUXpresso/LPCScrypt. However, if you copy the circuitry used on the LPCXpresso V2/V3 boards then you should be able to use the firmware as-is, using LPCScrypt. Note that we cant help debug any issues with a hardware development like this.
If lower performance is OK then you can copy the LPC11U3x-based debug probe used on LPCXpresso MAX boards. These boards use the mbed CMSIS-DAP debug probe software, and the source for that is available on the mbed developers' site. FYI, ARM also released source for an implementation of CMSIS-DAP on the LPC4322 on this site; see:
https://github.com/mbedmicro/DAPLink, although we cannot guarantee this will work with LPCXpresso/MCUXpresso IDEs.
Regards,
Brendon