It turns out that installing Apache 2.4 on CentOS 6.6 is a bit of a pain.

These are the notes I compiled after a lot of effort and many Google searches :) Scroll to the bottom for the sources!

Install the Development tools and dependencies:

yum groupinstall Development tools -y
yum install -y zlib-devel libselinux-devel libuuid-devel pcre-devel openldap-devel lua-devel libxml2-devel openssl-devel epel-release expat-devel db4-devel postgresql-devel mysql-devel sqlite-devel unixODBC-devel nss-devel
yum install freetds-devel -y

Get the latest source code for apr and apr-tools:

You can get that from here: Download - The Apache Portable Runtime Project

cd /tmp
wget http://mirrors.advancedhosters.com/apache//apr/apr-1.5.2.tar.bz2
wget http://mirrors.advancedhosters.com/apache//apr/apr-util-1.5.4.tar.bz2

Create rpm packages out of the apr-* source tarballs and install them:

This one takes about 3 minutes:

rpmbuild -tb apr-1.5.2.tar.bz2

Now install it:

yum -y remove apr-\*
yum localinstall -y /root/rpmbuild/RPMS/x86_64/*.rpm

This one took about 2 minutes:

rpmbuild -tb apr-util-1.5.4.tar.bz2

Now install it:

yum localinstall -y /root/rpmbuild/RPMS/x86_64/apr-util-*

The elusive distcache dependency:

The last dependency that we need is distcache - this also turned out to be the hardest to find:

cd /tmp
wget ftp://ftp.scientificlinux.org/linux/fedora/releases/18/Fedora/source/SRPMS/d/distcache-1.4.5-23.src.rpm
rpmbuild --rebuild distcache-1.4.5-23.src.rpm
yum localinstall -y /root/rpmbuild/RPMS/x86_64/distcache-*.rpm

Now build Apache 2.4:

Get the latest apache source for 2.4.x from here: Download - The Apache HTTP Server Project, in this example it's 2.4.18.

This took under 3 minutes

cd /tmp
wget http://apache.mirrors.pair.com//httpd/httpd-2.4.18.tar.bz2
time rpmbuild -tb httpd-2.4.18.tar.bz2

Install apache 2.4 and modules:

yum localinstall -y /root/rpmbuild/RPMS/x86_64/httpd*
yum localinstall -y /root/rpmbuild/RPMS/x86_64/mod*

Done!

Sources: