Instructions
Go to a location that is not inhabited by friendly non-player characters (NPC). This avoids the Ogrim Titan attacking and possibly killing an important NPC before you modify its behavior to act like a summon.
Press the "~" key to open the console.
Type "PlaceAtPC "ogrim titan", 1, 1, 1" into the console. This causes an Ogrim Titan to appear directly in front of you.
Click on the Ogrim Titan to select it.
Type "SetDispositon 100" into the console to cause the Ogrim Titan to be friendly to your character, like a summoned lesser Daedra, rather than hostile.
Type "AIFollow, Player, 0, 0, 0, 0" into the console. This command causes the Ogrim Titan to follow you around like a summoned creature would. If anything hostile approaches you, the Ogrim Titan should attack it.