3.8 How should I install a non-Debian program?
Files under the directory /usr/local/ are not under the control of the Debian package management system. Therefore, it is good practice to place the source code for your program in /usr/local/src/. For example, you might extract the files for a package named "foo.tar" into the directory /usr/local/src/foo. After you compile them, place the binaries in /usr/local/bin/, the libraries in /usr/local/lib/, and the configuration files in /usr/local/etc/.
If your programs and/or files really must be placed in some other directory, you could still store them in /usr/local/, and build the appropriate symbolic links from the required location to its location in /usr/local/, e.g., you could make the link
ln -s /usr/local/bin/foo /usr/bin/foo
In any case, if you obtain a package whose copyright allows redistribution, you should consider making a Debian package of it, and uploading it for the Debian system. Guidelines for becoming a package developer are included in the Debian Policy manual