The article may be based on 6.0.1, but is should work on 6.5, which runs an errata kernel for Red Hat 7.3 built by
http://fedoralegacy.org. The Fedora Legacy project provides security and bug fixes for popular end-of-life Red Hat products.
Kernel 2.4.20-37.7.legacy may already have support for the Smart Array 6i controller. A quick search in the module tree on my 6.5 test box revealed the cciss.o module. So try it out. If the installer doesn't load the module, follow the how-to. Note that you won't be able to use the "quick and dirty way", since the modules in the author's contribs folder are for Kernel 2.4.20-18.7.
You'll need to load another 6.5 box (or a fully-patched Red Hat 7.3 box running kernel 2.4.20-37.7) with the devtools (gcc-2.96-113 and related dependencies) to use as a build system. Yum works well for this, set up Red Hat and Fedora Legacy repos as follows:
[redhat-base]
name=Red Hat Linux 7.3 base
baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/7.3/i386/
[redhat-updates]
name=Red Hat Linux 7.3 updates
baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/updates/7.3/
[legacy-updates]
name=Fedoralegacy Red Hat 7.3 updates
baseurl=http://download.fedoralegacy.org/redhat/7.3/updates/i386
Note that you shouldn't run "yum update" with these repos active.
Eric