Radius authenticate support in Asterisk 1.4, any idea?

I 've searched a lot of maillist and website to find out the solution for radius authentication support in Asterisk 1.4 but I have nothing success found until now.
I have searched in asterisk source changes, event with asterisk 1.6 beta release, but I have not found any thing about external authenticate support for SIP register. So I wonder if asterisk development team want to support external authenticate or not?
Any body can help me for this solution? I am intend to write some patch for this problem but It may be had some thing siminar before

Thanks in advance