I based my setup guide on the Austin Constable's blog post. My version contains some tweaks that I had to make to the original guide in order to get it to work on my server. I hope it helps!

Preparation

1. Remove ffmpeg, x264 and faad2 to avoid confusion.

up2date -e ffmpeg x264 faad2 faad2-devel

2. Install the necessary build tools

up2date gcc gcc-c++ automake autoconf libtool subversion

3. Install the necessary libraries

up2date -u zlib-devel libmad-devel libvorbis-devel libtheora-devel lame-devel faac-devel a52dec-devel xvidcore-devel freetype-devel

Compile supporting libraries

1. Setup work area

cd ~
mkdir ffmpeg
cd ffmpeg

2. Compile and Install faad2

wget http://downloads.sourceforge.net/faac/faad2-2.6.1.tar.gz
tar xzvf faad2-2.6.1.tar.gz
cd faad2
autoreconf -vif
./configure
make
make install

3. Compile and install gpac

cd ..
wget http://downloads.sourceforge.net/gpac/gpac-0.4.4.tar.gz
tar -xzvf gpac-0.4.4.tar.gz
cd gpac
./configure

vi applications/Makefile
*** edit applications/Makefile and comment out the following lines:
#INSTDIRS+=osmozilla
#APPDIRS+=osmozilla
***

make
make install
make install-lib

4. Update the links to the shared libs

echo '/usr/local/lib/' > /etc/ld.so.conf.d/gapc-1386.conf
ldconfig

5. Compile & Install x264

cd ..
wget http://download.videolan.org/pub/videolan/x264/snapshots/x264-snapshot-20090119-2245.tar.bz2
tar xvjf x264-snapshot-20090119-2245.tar.bz2
cd x264-snapshot-20090119-2245
./configure --enable-pthread --enable-mp4-output --enable-shared --disable-asm
make
make install
ldconfig

Install ffmpeg

# You may need to install the subversion client
up2date -u subversion

cd ..
svn export -r16711 svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg
cd ffmpeg
./configure --prefix=/usr/local --disable-debug --enable-shared --enable-gpl --enable-nonfree --enable-postproc --enable-swscale --enable-pthreads --enable-x11grab --enable-liba52 --enable-libx264 --enable-libxvid --enable-libvorbis --enable-libfaac --enable-libfaad --enable-libmp3lame
make
make install

Done... That was easy! :)