GNU Radio / USRP building-linking

Hello all.

I am modifying a block (GSSM) and wish to include USRP code into it.
I think I am having linking problems and am wondering if someone could
point me in the right direction for including the USRP libs into the
build process. I have a block in which I have:

#include <usrp_standard.h>

usrp_standard_tx *utx = usrp_standard_tx::make (0, 64);

This compiles, but when I run the code I get:
ImportError: /usr/local/lib/python2.4/site-packages/
undefined symbol: _ZN16usrp_standard_tx4makeEijiiiiSsSs

What or where do I have to include -lusrp, et cetera?

Thank you for your time (again)