How Do I Update Apache to 2.2.24 On AWS Instance

Take a step back. The PCI scanner is blindly relying on version numbers and isn't taking into account that the vendor (which is eventually Red Hat) backports patches. Find out the exact vulnerability (get the CVE) and then use rpm -q --changelog httpd (or go to http://cve.mitre.org/cve/cve.html and https://access.redhat.com/security/updates/ ) to see if the fix has been backported. It is annoying to do; thank your lazy PCI QSA for the work.

I strongly recommend against installing from source. It breaks package management and you now become responsible for keeping apache up to date which is more annoying than verifying the backporting of fixes.