Si comme moi vous ne voulez pas attendre que la mise à jour soit déployé dans votre pays, voici la marche à suivre.
Cette méthode ne nécessite pas les droits root et n'effectue pas de wipe (effacement des données) .

*Pour une procédure en français laissez moi un petit commentaire ;-)

1. Install package "android-tools-adb"
2. On your Nexus, go to Settings > Development options and switch the toggle on. Then enable USB debugging under the "Debugging" menu group.
3. Dowload:
   • Nexus 10 (mantaray) - [LRX21P from KTU84P, 325MB] - Download Link
   • Nexus 10 (mantaray) - LRX22C from LRX21P, 8.4MB] - Download Link
   • Nexus 9 (volantis) - [LRX21Q from LRX21L, 38MB] - Download Link  (Issues)
   • Nexus 9 (volantis) - [LRX21R from LRX21Q, 17.9MB] - Download Link
   • Nexus 9 (volantis) - [LRX21R from LRX21L, 37MB] - Download Link
   • Nexus 9 (volantis) - [LRX22C from LRX21R, 25.9MB] - Download Link
   • Nexus 7 WiFi (2013) (razor) - [LRX21P from KTU84P, 389MB] - Download Link
   • Nexus 7 WiFi (2013) (razor) - LRX22C from LRX21P, 17.5MB] - Download Link
   • Nexus 7 WiFi (2012) (nakasi) - [LRX21P from KTU84P, 311MB] - Download Link
   • Nexus 6 (shamu) - [LRX21O from LNX07M, 192MB] - Download Link
   • Nexus 6 (shamu) - [LRX22C from LRX21O, 72.8MB] - Download Link
   • Nexus 5 (hammerhead Telstra) - [LRX21O from KTU84Q, 479MB] - Download Link
   • Nexus 5 (hammerhead) - [LRX21O from KTU84P, 479MB] - Download Link
   • Nexus 4 (occam) - [LRX21T from KTU84P, 394MB] - Download Link
   • Nexus 4 (occam) - [LRX22C from LRX21T, 16.7MB] - Download Link
   • HTC One M8 Gpe - [LRX22C from KTU84P, 528MB] - Download Link
   • HTC One M7 Gpe - [LRX22C from KTU84P, 511MB] - Download Link
   • Motorola Moto G (2013) GPe - [LRX21Z from KTU84P, 380MB] - Download Link
   • Sony Z Ultra GPe - [LRX21P from KTU84P, 397MB] - Download Link
   • LG G Pad 8.3 GPe - [LRX21P from KTU84P, 405MB] - Download Link
4. Plug your Nexus
5. In Terminal enter "adb reboot recovery" and press [return]
6. After the reboot, you will see the recovery screen (It says "no command"). Tap the [power] and [volume up] keys at the same time. A menu should pop up now.
7. If step 6 failed, just retry until the menu pops up.
8. Use the volume buttons to select "apply update from adb" and select it with the [power] button.
9. Back in Terminal enter "adb sideload ", (don't forget the space after sideload) then drag the update file onto the command prompt. This will automatically insert the filename for you. Now press [return] and wait.
10. Use the volume buttons to select "reboot system now" and select it with the [power] button.

Source:
http://www.reddit.com/r/Android/comments/2mgh8o/nexus_4_lollipop_ota_link_and_update_guide/
http://www.droid-life.com/2014/11/13/download-android-5-0-ota-update-nexus-5-7-10-4/
http://forums.androidcentral.com/sprint-epic-4g/72857-want-know-how-we-got-ota-download-link-look-here.html