Just went through a few dramas tonight to upgrade svn on my system from the old 1.3.2 version that is in the ubuntu repos to the latest 1.4.3.
I found this howto which gets you almost all the way there. Unfortunately amd64 uses will get a link error complaining that libneon.a needs to be compiled with the fPIC flag. This is easily fixed by changing the following line in neon/src/Makefile (line 28) after the configure step from this
CFLAGS = -g -O2
CFLAGS = -g -O2 -fPIC
then you make and install as per the howto.