Files ending in .I are regular installp files. The file MD5.summary contains the md5 check-sums for verification. The httpd filesets httpd-2.2 and httpd-2.4 require the APR project files apr and apr-util.
# bzip2 -dc aixtools.httpd-2.2.bundle.tar.bz2 | tar xf - # installp -d . -agX aixtools.apache.httpd.rte
The package should work from AIX 5.3 TL7 and later. If the package does not, please be sure and report it on the aixtools forums http://forums.rootvg.net/aixtools.
See Apache HTTPD Project Documentation for differences between httpd-2.2.X and httpd-2.4.X - especially if you are using, or want to use specific mods. Assume mods are not portable between the two versions.