Steps taken from from this StackOverflow answer by Lloeki
hdiutil attach ~/Downloads/RecoveryHDUpdate.dmg
pkgutil --expand /Volumes/Mac\ OS\ X\ Lion\ Recovery\ HD\ Update/RecoveryHDUpdate.pkg ~/Desktop/RHD
hdiutil attach ~/Desktop/RHD/RecoveryHDUpdate.pkg/RecoveryHDMeta.dmg
~/Desktop/RHD/RecoveryHDUpdate.pkg/Scripts/Tools/dmtest ensureRecoveryPartition / /Volumes/Recovery\ HD\ Update/BaseSystem.dmg 0 0 /Volumes/Recovery\ HD\ Update/BaseSystem.chunklist