Okay, I know, nobody wants to convert to RMVB, and somebody's going to yell at me, but I can't seem to find anything that will let me convert to RMVB. I keep a lot of video on my computer at a time, and rmvb helps me manage that, but I can't find a way to convert to RMVB with OS X. I've got a PPC Mac, so I can't just run Windows. I've got FFMpegX set up to decode RMVB, but is there any way to set it up to code them, or is there anything else I can use?

Thanks!