How to upload photos to iCloud Photo Library on iPhone without Wi-Fi?

I just upgraded to OS X 10.10.3 and decided to try out the Photos app. So I enabled iCloud Photo Library on my iPhone to upload some photos.

However, it says that I need Wi-Fi to upload photos to iCloud. The problem is I don't have a Wi-Fi connection, I only use the cellular connection for all my Internet needs.

Is there a way to upload photos to iCloud via cellular?

Unfortunately, the answer is no:

When you turn on iCloud Photo Library on your iOS device or Mac, your photos and videos will upload after you connect to the Internet with Wi-Fi and your battery is charged.

https://support.apple.com/kb/HT204264#upload [emphasis mine]

My father has the same issue he lives in a area where he can't get internet. We have a hack option takes two iPhones or a iPad with Cellular what you do is the phone you want to upload photos off you tether to the iPad or iPhone it will think its on a wifi network and start uploading photos. so take a old iPhone put your sim in it and tether it to the phone and then it will work its a hack and is a pain but does work.

iCloud Photo Library uploads now seem to be available via the Cellular Data "Unlimited Updates" feature.

Settings > Photos > Cellular Data > Unlimited Updates

Unlimited Updates
Turn on for unlimited use of cellular data to upload and download to iCloud Photos when you are not connected to Wi-Fi. This may cause you to exceed your cellular data plan.

This option appears to have launched in 2017 with iOS 11.