This mod can be flashed via TWRP or CWM recoveries on odexed and deodexed stock based ROM's and will enable SMS and Tethering options in Settings. By default SMS will appear in Hangouts as per the Nexus 5.
Revert is only for stock odexed users. Should you need to restore a deodexed ROM simply reflash it.
LRX22G SMS WiFi Tether
LRX22G Revert to stock
KTU84P SMS WiFi Tether
KTU84P Revert to stock
KTU84L SMS WiFi Tether
KTU84L Revert to stock
KOT49H SMS WiFi Tether
KOT49H Revert to stock
KRT16S SMS WiFi Tether
KRT16S Revert to stock
If you want pure WiFi tethering and no SMS then use @xtoudi's mod, found here;
[MOD][4.4][KRT16S/KRT16O] Tethering/Wifi Hotspot for the Nexus 7 3G
For USB tethering, you will need a kernel with RNDIS included, @kloon15 has compiled a stock one here although I don't know if this has been updated for Lollipop.
2013 Nexus 7 version of the mod is here
@fisha21 for putting up with my constant ranting about Google removing SMS and helping out.