# in your case, it is /opt/something
export PREFIX=$HOME/prefix

# 64 because my laptop is 64bits :)
export PKG_CONFIG_PATH=$PREFIX/lib64/pkgconfig/
export XDG_DATA_DIRS=$PREFIX/share/:/usr/share/
export LD_LIBRARY_PATH=$PREFIX/lib64:$PREFIX/lib/
export PYTHONPATH=$PREFIX/lib64/python2.4/site-packages/:$PREFIX/lib/python2.4/site-packages/:/usr/lib64/python2.4/site-packages/:/usr/lib/python2.4/site-packages/

#then I run all in a separate dbus-session:
dbus-daemon --config-file=/etc/dbus-1/session-jabber.conf --print-address

/etc/dbus-1/session-jabber.conf is modified from session.conf because I installed everything in a prefix...

I use the first output line to :
export DBUS_SESSION_BUS_ADDRESS=unix:abstract......

Then I start empathy :-)