Best ever game on PS2 and worst ever port on PC, by the way you can get mouse working in RE4 search in google and i am sure you will find the required loader.
Biohazard 4/Resident Evil 4 Mouse Support
Copy loader etc into main game folder. Run Loader, Setup as desired.
Although default settings seem good, and lauch the game through loader
Enjoy
History:
1.2
-Added: Support manually load game, compatible with 3D-Analyzer
-Added: Custom mouse settings supported
-Added: Support Run / Cancel key
-Added: Support camera up & down when not in Weapon / Knife Ready mode
-Added: Loader will save settings if exit without loading game
-Fixed: A bug where the loader forget to release the process handle when exit
1.1
-Added: Chinese (Simplified) UI supported
-Added: Custom keyboard settings supported
-Fixed: A bug in device unacquire
-Fixed: A bug where the mouse cannot hide correctly if game.exe lost focus while loading
-Changed: Loader no longer wait for game.exe to terminate
-Changed: Mouse cliped in client area instead of the center of the screen
1.0
First release