I compiled buildroot with external toolchain, because of internal buildroot bug. It seems to be exist in last release. When I tried to compile buildroot and toolchain for arm - it didn't work. My board didnt recognize this filesystem.
Yesterday I downloaded buildroot snapshot "buildroot-20090420". Internal toolchain is OK now. And almost everything is compiled now. You only need to choose target architecture "arm" and cpu "arm920t".
Use updated manual