modifying inbound link text calc

[Insurance Squared Inc.]

I'm trying to get rid of some spammy sites in our index. 

First, I wonder if anyone has any suggestions on changes to the default 
install config of Nutch that will help drive better sites to the top and 
spammier sites down.

Secondly, I boosted the inbound anchor text config - but if anything 
that made things worse.  A lot of the spammier sites heavily use search 
terms intheir  internal anchors.  So I'm wondering - is there any easy 
way to distinguish between anchor text from within the same domain vs. 
anchor text from external domains, and give them different weightings?  
I expect this isn't the case currently - anyone have any opinions on how 
difficult this would be to change?

Thanks,
g.