I wouldn't dare that. Remember what malicious code was found in other Elbox drivers and what could happen if you patch them.
On the other hand it's easily possible to patch expansion.library in order to fake the existance of Elbox hardware. I successfully ran AllegroCDFS on WinUAE this way.
But it's not worth. As I mentioned above, AllegroCDFS cannot read a single DVD more than CacheCDFS. You can as well use CacheCDFS which comes free with OS 3.5 and 3.9.
Bye,
Thomas