Building seyon. Where xmkmf?

OK, I want to try the X windows based serial
port terminal program seyon. I downloaded the
source. The docs say to "run xmkmf" to begin
the build process.

I don't have this xmkmf on my Red Hat 7.2 or 7.3
system. I find references to it all over the
net but no place where I can download it.

A) Does anyone know where I can download this
makefile generator utility?

OR

B) Can I build seyon without this utility,
somehow using the Imakefile to generate a real
makefile?

Or are there other options to get seyon?

Alan