Quoting Alex [off-list ref]:

Pavel, Omar and all,

thank you very much for your support. However, I still get the error message:

                 from <command-line>:0:
/usr/src/compat-wireless-2011-06-30/include/linux/compat-2.6.34.h:23:
error: redefinition of 'netdev_name'

It takes some time to propagate patches.  The patch appeared in  
compat-wireless-2011-07-01, which is available now.

BTW: One more question: There seems to be a module "carl9170" in the
2.6.39.2 kernel. Does this replace compat-wireless? Do I only need
this module to get the wlan in monitor mode? (please excuse my
question, I am really new to this...)

You can try it.  The point of compat-wireless is to make the current  
wireless drivers available for older kernels.  If you kernel is not so  
old, you make have the functionality you need in your kernel already.   
But if you want to use the older Debian kernel, compat-wireless is the  
only option.

-- 
Regards,
Pavel Roskin