It didn't trigger from in-game which is weird since it's LIVE and that usually handles patches via a (often somewhat forceful. ) auto update mechanic in-game from the interface.
Anyway someone managed to find the download link so here's that, maybe it'll help.
Link (X-Box download website, cab file that can be unpacked more or less like a regular rar or zip archive and then a setup file and patch related cab file plus a MSI inside.)
(/f as a command parameter to setup.exe incase the patch doesn't find anything or stalls such as via a shortcut to setup.exe it would be as a generic example " C:\deadrising2otr\zpatch\setup.exe /f c:\deadrising2otr\ "