Changing library paths?

[Remington L.]

I want to change the library path to a given executable. Example: I have
"foo". When I do a ldd foo it comes up with:
Libc.so.4 => /usr/lib/libc.so.4

I want to be able to change the path to say something like
/compat/linux/lib/libc.so.4

How is this accomplished?

Thanks