The /sethit system in SA:MP was an absolutely horrible idea and I have even proposed its removal as it became a means for "legal" DM, and gave admins a lot of headaches from having to deal with its abuse.
You can totally roleplay the hit contract, with additional advantages over the script system. The target can still die, the money can still be transferred, the hit itself will generate roleplay, and the hitman can turn on his contractor if he is scammed or cheated on.
RP it.