sendmail modification needed for mimedefang to work FC2

[Julian Underwood]

Hello, was wondering if someone could offer a suggestion.

I'm running FC2, with sendmail-8.12.11-4.6.  I'm wanting to set up spam
filtering (and possibly virus filtering) on my working sendmail mail
server.  From the posts I've read on this list, it looks like MIMEDefang
is a good way to go about intergrating sendmail with spamassassin.  I've
been following the HOWTO linked off of the main MIMEDefang page and ran
into this:

In versions prior to 8.13.0, sendmail did not support mail filters by
default, and must be compiled with filter support enabled by defining
-DMILTER. To do this, create devtools/Site/site.config.m4 with the
following lines:

dnl Milter
APPENDDEF(`conf_sendmail_ENVDEF', `-DMILTER')
APPENDDEF(`conf_libmilter_ENVDEF', `-D_FFR_MILTER_ROOT_UNSAFE')

----

As I do not wish to blow up my mail server, I'm asking what would be the
best plan of attack?  Upgrade to the latest Sendmail, if yes, how?  From
tarball?  I did not see any updated sendmail RPM's for FC2.  Or should I
install the sendmail-8.12.11-4.6 source and rebuild it with the above
lines?
Or maybe I should be looking at an easier way to combat spam?  If so, what?

I'm a sendmail newbie, so whoever responds to this message please don't
spare any details!

TIA,

Julian