I probably don't understand this as well as you do (obviously), so pardon some of the obviousness of my question.

I realize opcode 0x6a is what refers to OP_RETURN. I noticed this in the HEX for some of the TX's already on the blockchain that have OP_RETURN output scripts. It seems (if I get it right) that it is something like 0x6a

Not too sure what you meant when you said to put the opcode 0x6a in front of the script followed by the length prefix.

Since the bitcoind client does not let you specify output scripts (per my knowledge) when creating a raw transaction, I am going with the idea that I have to take the output of createrawtransaction, and modify it to additionally include OP_RETURN somehow.

What approach were you referring to?