AWS KMS ECC_SECG_P256K1 decoding to serialized tx

Hi!

I am using AWS KMS with a custom-managed key to sign and verify transactions using an asymmetric ECC_SECG_P256K1 key for Tron network blockchain. I was able to sign and even verify the transaction through a AWS Lambda function, though what I need know is to transform the DER encoded signature into a hash and serialized tx compatible with the tron network.

I am perfectly able to retrieve R and S values of the signature but now I need to serialize it properly.

What is the proper way to accomplish that?

Thanks in advance!!