Question about using libraries without ./compile --with-library

I know you can use ./configure --with-gd to compile gd with php and same with ming, to make flash movies, for example However, I noticed on source code one tutorial showed the php script link straight to the ming .so file, which made me wonder *IF* that was because they didn't use ./configure...is it possible to do that with gd and others? To use php and that library *without* ./configure? I found that odd, unless I misunderstood what they were doing in that ming flash example by connecting to that .so file Is that something you can do with ming, gd library or any other without ./configure option? If that is the case, what are the performance differences in using such a method? Is it such a bad idea, that I should avoid such practices? If I need to elaborate and show a code example, I will. I just never really knew of such a way to use a library. Thanks for your time Joel