I needed to update the tor revision that is available for an older installation of OpenWRT. The following are the procedures I used to build Tor for OpenWRT Backfire 10.03.1-rc4 r24045 using a OSX workstation.
The default FS configuration in OSX does not support case-sensitivity. Therefore we will download the SVN and all files onto a local sparse disk image we create with
hdiutil create -size 700m -type SPARSEBUNDLE -fs "Case-sensitive HFS+" -attach -nospotlight -volname openwrt_tor openwrt_tor