I currently use the following procedure to install Fixes snapshots on Ubuntu Lucid since other ways have proved quite hard to me:
- add lazarus testing repository to software sources
- install current FPC from the repository
- download Lazarus source, unpack and compile with "make clean all" then if compilation went ok, I do "make install" so it gets installed to /usr/local/share/lazarus
- manually setup links, icons etc.
If you need newer Lazarus, like next release testing snapshots, or from SVN, download and install newer FPC debs from the snapshot page.
I've chosen this path since fresh Lazarus debs won't install on my system because of dependency problems, but manual install is just as easy and with no obvious drawbacks. I install FPC from the repositories/debs since the installation works flawlessly, yet manually installing it can be a pain...