To install regutils, you need to edit the Makefile and check the variable
settings at the top of the file.  These include:
    Install dirs:
	BINDIR
	SCRIPTBINDIR
	LIBDIR
    Program locations:
	PERL
	FIND
	XARGS
    Permissions:
	USER
	GROUP
    Compiler stuff:
	CC
	DEBUG_FLAGS
	CFLAGS
See the comments in the make file for info on these.  Once you're happy
with the settings, run
    make
and finally
    make install