You have to create a folder called "INSTALLEDDLC" inside the BLESXXX/USRDIR folder, not where you dumped the game, but where the game data is installed.
Put the .ESP file(s) in that folder, along with a DLCLIST.TXT and PLUGINS.TXT file you have to create. In those two txt files put all the filenames of the .ESP files you have in upper case.
Doesn't work with everything tough, tested and working with: "Legendary Mastery" (stats and attributes go above 100), "Quest Award Leveller" and "Heroes Retreat" (player house with a trader and enchantment/spellmaking altar).
Doesn't seem to work with new textures.