Try building and uploading MIPS toolchain on one of the buildbots.

buildbot/file_up_down_load.sh

 #!/bin/bash
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 #@ This script for up/downloading native client toolchains, etc..
 #@ To manually inspect what is on the store servers point your
 #@ browser at:
 #@ http://gsdview.appspot.com/nativeclient-archive2/
 
@@ skipping 144 matching lines @@
 #@ pnacl_linux_x86
 #@ pnacl_mac_x86
 #@ pnacl_win_x86
 
 UploadToolchainTarball() {
   local rev=$1
   local label=$2
   local tarball=$3
 
   ComputeSha1 ${tarball} > ${tarball}.sha1hash
-  UploadArchive toolchain/${rev}/naclsdk_${label}.tgz.sha1hash ${tarball}.sha1hash
+  # UploadArchive toolchain/${rev}/naclsdk_${label}.tgz.sha1hash ${tarball}.sha1hash
+  UploadTrybot toolchain/${rev}/naclsdk_${label}.tgz.sha1hash ${tarball}.sha1hash
 
   # NOTE: only the last link is shown on the waterfall so this should come last
-  UploadArchive toolchain/${rev}/naclsdk_${label}.tgz ${tarball}
+  # UploadArchive toolchain/${rev}/naclsdk_${label}.tgz ${tarball}
+  UploadTrybot toolchain/${rev}/naclsdk_${label}.tgz ${tarball}
 }
 
 DownloadPnaclToolchains() {
   local rev=$1
   local label=$2
   local tarball=$3
 
   DownloadArchive toolchain/${rev}/naclsdk_${label}.tgz ${tarball}
 }
 
@@ skipping 105 matching lines @@
   Usage
   exit -1
 elif [[ "$(type -t $1)" != "function" ]]; then
   echo "ERROR: unknown function '$1'." >&2
   echo "For help, try:"
   echo "    $0 help"
   exit 1
 else
   "$@"
 fi