A not-quite-newbie question

[Ken Martwick]

     If one wants to run a Linux program that uses libraries
earlier than those in the distribution, one can download the
libraries.  But then, since (in Slackware at least) they are
installed in some obscure subdirectory, how can the program
be given access to them?  At least in the case of "X" li-
braries, the designations are the same as later versions.
Anyone for an exclusive-or link?
Ken Martwick