[arch-general] Question about installing libraries

Hi all, I am learning and learning more in Arch linux, but I have a question. There are a few programs that I use and I am not able to find all the dependencies in the Arch repositories, and some of th elibraries are a little old and the developers have .deb packages for them. So my question is if I get a such package, may I just extract it, unpack the data.tar.gz and copy the libraries into /usr/lib? For example, I now need to use pygame1.8 and there is 1.9 in the arch repository. What do you think? Many thanks, Christian