SVN is just source control management, so to install it you will have to get the source code of the software and compile it yourself if a pre-made package does not exist.
You can do this by getting the latest source code from their SVN repository (using
svn checkout), or by download and unpacking a .tar.gz.
After that, the most common install procedure is to go to the folder with
makefile and do a
make and then a
make install which will compile it, then install it.
However for this particular package it looks like a fair amount of knowledge is required to get it working, so you might want to familiarise yourself with the *nix environment and memcached first.