A living Entity is one that has health and that can die.
Unlike IEntityLivingBase however, players aren't IEnitiyLiving objects!

It might be required for you to import the package if you encounter any issues (like casting an Array), so better be safe than sorry and add the import.
import crafttweaker.entity.IEntityLiving;

IEntityLiving extends IEntityLivingBase. That means all functions available to IEntityLivingBase objects also are available to IEntityLiving objects.

ZenGetter	ZenSetter	Type
ZenGetter attackInterval	ZenSetter ​	Type int
ZenGetter attackTarget	ZenSetter attackTarget	Type IEntityLivingBase
ZenGetter canBeSteered	ZenSetter ​	Type bool
ZenGetter canPickUpLoot	ZenSetter canPickUpLoot	Type bool
ZenGetter canSpawnHere	ZenSetter ​	Type bool
ZenGetter getLeashedToEntity	ZenSetter ​	Type IEntity
ZenGetter isAIDisabled	ZenSetter isAIDisabled	Type bool
ZenGetter isAIDisabled	ZenSetter isAIDisabled	Type bool
ZenGetter isColliding	ZenSetter ​	Type bool
ZenGetter isLeashed	ZenSetter ​	Type bool
ZenGetter isLeftHanded	ZenSetter isLeftHanded	Type bool
ZenGetter isNoDespawnRequired	ZenSetter ​	Type bool
ZenGetter maxSpawnedInChunk	ZenSetter ​	Type int
ZenGetter ​	ZenSetter moveForward	Type float
ZenGetter ​	ZenSetter moveStrafing	Type float
ZenGetter ​	ZenSetter moveVertival	Type float
ZenGetter renderSizeModifier	ZenSetter ​	Type float

Requires no parameters.
Returns nothing.

ZenScript
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ebtLiv.playLivingSound();

Requires no parameters.
Returns nothing.

ZenScript
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ebtLiv.spawnExplosionParticle();

Requires an IEntityEquipmentSlot object and a float.
Returns nothing.

ZenScript
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ebtLiv.setDropChance(IEntityEquipmentSlot slot, float chance);

Requires no parameters.
Returns nothing.

ZenScript
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ebtLiv.enablePersistence();

First method requires an IEntity object, a boolean and returns nothing. Second method requires two booleans and returns nothing.
Third method requires an IPlayer object and returns a bool.

ZenScript
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ebtLiv.setLeashedToEntity(IEntity enttiy, boolean sendAttachNotification);
ebtLiv.clearLeashed(boolean sendPacket, boolean dropLead);
ebtLiv.canBeLeashedTo(IPlayer player);