This mod revamps previous versions of the Horse Commands plug-in.  This mod should work with any horse (whether stock Bethesda, or player made).

Snak Gra-Bura is now offering horse training courses.  Her basic course will allow you to teach your horse to "follow", and "stay" on command.

Advanced classes will allow you to train your horse to modify its instinctive behavior.  This includes:
Having a horse follow you or stay by default after dismounting.
Having a horse go to the nearest stables instead of the Chestnut Handy Stables when they are lost.
Allowing a horse to follow you into towns.
Allowing a horse to follow you into planes of Oblivion.
Having a horse stay and defend itself during battle, instead of fleeing.

All coursework materials necessary to complete the class are included in the reasonable enrollment fees.  Books provided offer additional insight to the behavior of horses.