Here you go: http://www.skinnyv.com/misc/Unpacked_ARC.rar
I couldn't get the latest version of the tool to work, it crash when I start it on Windows XP even after installing the shitload of DLL it require. I tried the first version and it worked, the only issue is that I do not think that version allow you to repack the ARC.
It's weird tough as I did some poking around the Mega Man X4 files and the ARC files you wanted extracted have a slightly different file size compared the the one I had. The content seem to match except for a few of the extracted bin files... Wonder if there's different revision or if one of us improperly extracted them from the disk. In any case, to avoid problems, I extracted the one you provided.
Oh and it is true, the Japanese voice sample are still present in the US version's file, dunno where the pointer are stored though.