[R] How to fix false positve rates?

[Anderson de Rezende Rocha]

Dear R-users, 

I have a set of 12000 image samples. I can divide this set into two
categories: training and testing. I need to classify the test set into
a two qualitative outputs: true or false for some characteristic. 

To do the classification I'm using the packages SVM in e1071 library
and LDA in the MASS library. However, I'm with a great number of FALSE
POSITIVE CASES in both classifiers, about 10/15%. 

1) How can I use these classifiers with a fixed 1% FALSE POSITIVE RATE?

2) Could anynone indicate me a non-linear SVM classifier R-package?
3) Could anynone indicate me an ADA-BOOST classifier R-package?

Thanks for all. I'm anxiously wait the answers. Best regards. 

*************************************************
|Üñðë®§µñ| - Anderson de Rezende Rocha
Bacharel em Ciência da Computação - UFLA
Mestrando em Ciência da Computação - UNICAMP
Esteganografia e esteganálise digital
UNIVERSIDADE ESTADUAL DE CAMPINAS, SP - BRASIL
< http://andersonrocha.cjb.net >