Do you want to be a vampire lord without starting the Dawnguard questline? Or are you just testing your new mod setup and want to test if vampire mods work? Then I have great news for you!

This mod adds a book that either infects you or cures you of vampirism with Vampire lord transformation included. 

1.) via console - player.additem xx00A665 1 (exact FormID can be obtained with help "Toggle Vampirism" command (quote marks included))
2.) via AddItemMenu 
3.) in-game strongbox located at the Riverwood gate (see images) 

Use your favorite mod manager (NMM, Vortex, MO) or extract mod into Data folder in your Skyrim installation folder.
I would recommend to back up your save, even though this mod should not be really game breaking with one simple script.

------------------- Issues -------------------

The only issue found so far is pretty obvious one. When you go through the Dawnguard questline, when you get to Harkon with Serana, the dialog ends with you being expelled from the castle (at least it did for me). If you want to continue the questline as vampire, cure yourself before talking to him, then it should work fine.

It should be compatible with anything. the only thing that might go wrong is the strongbox if any other mod edits Riverwood gate.

------------------- It's not working! -------------------

Please tell me what is wrong in comments or in bug reporting tab and I'll see what I can do.