> > where to find the sources (kernel) of the RC versions e.g. 1.6.2 RC 4
> > on releng.netbsd.org ?
> 
> You can get it from anoncvs:
> cvs co -r netbsd-1-6-PATCH002-RC4 src 

revision tag "netbsd-1-6-PATCH002-RC4" will freeze you at 1.6.2 RC4 and no other

branch tag "netbsd-1-6" will get you the LATEST 1.6.x i.e. RCx RELEASE or whatever:

cvs co -r netbsd-1-6 src