HSF+HDA Kernel patch for 2.6.20

Hi. I have a HSF modem with HDA support. I'm trying to load the module 
for HDA, but I received some errors about external functions.

Looking in GPL directory, I see kernel's files, and some files having 
functions need by hda module.

In www.linuxant.com/drivers/hsf/downloads-patches.php patches does not 
exist.

hsfconfig -p don't return any patches too.

Somebody have a patch to apply in this kernel to support a hsf+hda 
modem? Or how to procced to apply manually this GPL files in kernel 
directory?

Regards,
Rodrigo Luiz.