You can download the fpc as a tar file that contains an installscript.
Your package manager however will then not be aware of the installation of fpc.
After that download the sources for fpc and the sources for Lazarus (the latter is easiest via svn), best in some subfolder of you home directory.
Then manually build Lazarus.
The advantage of this is that you Lazarus is local to you.
The disadvantage is that you will have to install some devel packages before you can actually build Lazarus, otherwise the linking will fail.
You need devel packages for libc, glibc, gtk2, gdk-pixbuf, cairo and some more.
Installing gcc might take care of some of those.
Also you need binutils installed (make etc.)
I only ever once installed fpc/Lazarus via my packamanager (on Suse 10.0), after that I changed to the above mentioned way of getting the compiler and Lazarus.
Finding out what devel packages you need is the hard part.
However, if linking fails due to a missing lib, it will mention what lib this is (and nee then need the devel package for that).
Bart