Look I know, its bad... But all the good modders are staying busy with other projects and I just really wanted to play him, I mean they put them in the story and everything what a tease!!!
And don't give me that "its a stretch crap" all that time he spent with Glover, with access to the computers and the robot that gives the CAC powers, its not at all a stretch he could figure out how to imbue himself with some until he can find his death note. Not to mention if I recall correctly Light was noted as being a pretty top of the line in regular human physical ability to begin with. The biggest stretch is how he'd convince Ryuk to actually fight with him, maybe promised to force an entire dimension that would make apples or something.
If your an older version of the game you may need to swap the sig file and rename the pak.