Right i managed to stumble across a Chevrolet flip key that is more suitable then the vauxhall version, especially because you have to mod it to suit the mk4. I will explain using pictures below
Vauxhall Key is on the left
The Chevrolet key blade is the same style as the MK4 key blade and the key casing is suited to the blade so you dont have to hack away at it like you would if you were using a MK5 key.
The best thing about the chevrolet key is that it isn't glued together like the vauxhall key is, infact if you remove the badge on the back of the key, it will reveal a small screw. Unscrew this screw and the whole case will come apart without having to cut it open like you would have to do with the vauxhall key.
I will do a how to if people want to, but obviously i need to complete the mod first. I will let you know!