rpm target option and compiler flags for rebuild

[Jacob L Anawalt <anawaltaj cachevalley com>]

Hi rpm guru's,

I have a couple of questions about rpm (v4.0.2-8). If the book Maximum 
RPM, or another source covers these topics for rpm v4 in depth, please 
let me know.

rpm --target=k6 --rebuild <somepackage.version.src.rpm>:

I would like to easily rebuild a slew of packages specificaly for my AMD 
K6-2 3Dnow with some custom compiler optimization flags.

I have tried rebuilding packages with the above command and although the 
package will call itself package.version.k6.rpm when it is done, placing 
itself into /usr/src/redhat/RPMS/k6/ it will not compile with 
--march=k6, although a --target=i586 will compile with --march=i586.

Is it possible to pass other compiler options into the rebuild from the 
command line? Where is a good listing of environment variables accepted 
and those set by rpm v4?

I know that I can modify the spec file for the package, or if needs be, 
the config.in or similar files in the package's source directory, but 
that quickly moves me away from a simple rpm based rebuild and install.

Thanks for the educational responses. Please cc me since I am not a list 
member.

Jacob Anawalt