A custom Windows Phone 7.8 ROM cooked by OP for the Nokia Lumia 710 is now available on XDA-Developers.
The ROM, which is OS version 7.10.8835.35 and covers all the official languages is fully unlocked with Root Tools and comes with 60 wall papers and features:
â€¢60 New wallpapers
â€¢Bazaar 1.7 was installed
â€¢Keep Wifi Alive was installed
â€¢Full Unlock V3 by ultrashot
â€¢MAX Apps in taskswitcher is 500
â€¢Updated Camera; added Panorama, Smart Group Shot, Action Shot, Self Timer.
â€¢Added Network to settings by Nokia.
â€¢You can install apps from Internet Explorer
â€¢Added new accents (dark teal, light blue, dark blue, dark pink, dark purple, htc, gray, black)
â€¢BT File Transfer has been installed
â€¢Speed up drawing graphics (Improved speed)
â€¢Added EXE Launcher, you can run EXE files
â€¢Added static ip
â€¢If you turn on silent profile, camera will work without sounds
â€¢Removed Contacts Transfer
â€¢Added theme HTC
â€¢Added wallpapers from htc
â€¢Added Root Manager by ultrashot
â€¢XAP Deployer has been installed (in Settings)
â€¢File Explorer has been already installed
â€¢WPH Tweaks 0.5 has been installed (in Settings)
â€¢Added Google and Yandex as search engine
â€¢WP7 Root Tools, modded edition.
For installation instructions and to read more see the XDA-Developer thread here.