For compatibility reasons, I want to install
subversion-1.4.4-r4 rather than the latest.
If you want to install something that is not in the portage tree, you will have to find/create the ebuild yourself.
From there you can add it into the tree and install it.
As webdestroya said, you'll need to find the old ebuild and put it in an overlay. The first part of that is easy enough, since the Portage tree is stored in a CVS repository which is browsable online (you can also check out a copy if you want, although to get just one ebuild that's unnecessary). Here's a direct link to the
Once you get the ebuild, you should put it into a local overlay, which is also reasonably easy. If you already have a local overlay you know how to do this ;-) but if not: Create the directory
where all the files should be downloaded from the CVS repository's web interface. Once you have the files in place, run
which will create the manifest file that lists checksums and file sizes for the ebuild, the patches, and the source archive. (If this were a more recent ebuild, you'd be able to download the manifest from the CVS repository, but back when this ebuild was current, Portage used a different system for checking file integrity.)
Finally, once the files are in place, add the line