Steam://install/22480 should do it.
(22480 being the AppID for GECK NV Edition, 22380 being New Vegas itself.)
EDIT: Works as a URL, it's a Steam install command such as these others.
http://developer.valvesoftware.com/wiki/Steam_browser_protocol
EDIT: Ah it's not active yet it seems.
EDIT: To validate and verify this one can also use the following, however as per above since it's not active it can't really be installed or used yet or the install script would have worked.
Steam://validate/22480
EDIT: Just about finished filtering trough FalloutNV.esm with FNVEdit also.
http://www.newvegasnexus.com/downloads/file.php?id=34703
(Copied FalloutNV.esm before it updated, another copy after it updated and named it FalloutNV.esp, copied back the pre-patch verson and then edited FalloutNV.esp in FNVedit to actually be a esp file and depend on FalloutNV.esm then just filter it, it'll take quite some time, and finally remove all original/identical records from FalloutNV.esp to leave just the altered/updated content - gives a clear definition and view on what exactly changed or updated instead of just the listed balance changes Steam news article about the update shows, of course for any exe changes the NVSE steam or similar will have to look at that, I can't see anything of what that has done though it seems they've already mentioned a few things during that NVSE beta 9 update recently - http://www.gamesas.com/index.php?/topic/1168320-beta-new-vegas-script-extender-nvse-v1/page__view__findpost__p__17541849 )
EDIT: That's a lot more changes than I thought there would be.
http://img849.imageshack.us/img849/7866/12345r.jpg
(Updating the mods I use is going to take some time as usual but comparing against this should simplify the process this time.)
(To name some things all cowboy themed hats now use a DT of 1 instead of 0, Nuka-Cola has a duration of 25 instead of 20, Gannon Tesla armor is medium instead of heavy and much much more.)