Don't let me stop you from trying but if you were planning on getting Mabinogi to run using an older version of HackShield, it won't work.
There's other issues that will prevent the client from running, but even if you get past all of them and keep it from updating, you won't be able to log in.
Please read

for more about that. Information about some of the HackShield files are sent as part of the communication. There are slight differences between how it works for Mabinogi and how the poster describing how it worked for Requiem, but the general idea is there. Expect more work in store for you if you continue on this route.