No that is impossible, until not Electbyte will release the source code.
Um, You don't need the source code for Mugen in order to modify it, it is basically open source but it is however copyrighted I think but not positive as I believe it was dropped by Electbyte some time ago, however many people have made altered versions of Mugen, Examples are Shugen Do and InfinityCat. Where theres a will theres a way to do anything, I just don't think anyone has the will to do a filtered look Mugen other then you maybe.
I do believe Electbyte is going to make a new version of Mugen and make it a legit game system as they have seen the potential with Mugen even after they abandoned it but this may be a rumor. Regardless of that Mugen is and will always be my favorite 2d fighting system ever. Here is a link to their final released statement but I am not so convinced it is really them.http://elecbyte.com/faq/