You need an X server on your LOCAL system which has the LBX extension compiled in. Unless you explicitly told it not to when building it, X11R6.3 servers automatically enable LBX. Also, all XFree86 3.3 servers have LBX enabled by default.
You can use the xdpyinfo command to see if your server has the LBX
extension: run xdpyinfo and look at the list just under "number of
extensions"; you should see "LBX" listed there.
Next, you need to get an lbxproxy program compiled for the REMOTE
system. This is the tricky part. If the remote system is not the same
type as your local system, the lbxproxy on your local system will
do you no good, of course.
There is unfortunately no "broken out" distribution of lbxproxy, so
you will have to either (a) get and build most, if not all, of X11R6.3
for the remote system, or (b) find someplace to get a pre-compiled
lbxproxy binary for your system. The latter is much simpler of
course.
The lbxproxy is simply a single executable. There are no
configuration files, resource files, etc. associated with it.