I used the CentOS version source rpm as the basis for the SME version. The CentOS rpm (which is based on rhel version) was up the SquirrelMail 1.4.6. I bumped up to the next 1.4.7 for the build. I changed the installation directory and had to set up a custom template fragment for the httpd.conf so the SquirrelMail would not be lost at another SME upgrade. I additionally used some of the install/removal scripts from the SME6 (SquirrelMail) rpm by Ergozd.
The package is ready but I'd like send it to a couple people to test out before releasing it. PM your email if your interested.
Rigger