TempIk 
Bakes the selected bones or controls to a new temporary IK Chain with the animation applied to it. This can be usefull for doing a quick mocap cleanup on a raw armature, without doing any retargeting to a new rig, or just locking specific limbs in space - for example an elbow leaning on a table, fingers locking into something. Anything that requires IK but is not available at your current rig, or you just want to use Temp IK's snap and smart bake system.
Add an Extra IK Ctrl Bone
Adds an extra IK bone controller to the tip of the chain. When this option is turned on, it will create an extra bone in the tip of the chain, this bone will only control the ik chain target position. When this option is turned off, it will use the last selected bone in the chain as the ik controller. The last selected bone will also get the rotation values from the ik controller. This option is turned on by default when selecting only one or two bones in a chain. If more bones are selected it will be turned off by default
Example
Selecting 2 bones, turns on Extra IK Ctrl by default, and adds an extra bone at the tip of the chain.
Selecting 3 bones, turns off Extra IK Ctrl by default, and the third bone is used as the IK Ctrl, influencing the original bone rotation as well.
Add Pole Target
Adds an extra pole target bone controller to control the knees or elbows. If this option is turned off then the base bone rotation will be used to adjust the knee/elbow vector. The pole target is still not completly precise. You can get better precision when baking to tempIK using the base bone, however better precision will be applied soon with the new bake.
Example
Temp IK Without Pole Target, using the base bone to control the knees.
Temp IK With Pole Target.
Multiple IK chains
Temp IK Can create multiple IK chains from multiple selections. If the selected bones are part of different chains of hierarchies, it will create new IK ctrls for each chain of the bones separatly. This is especially useful for quick setup on raw armatures.
Warning
If the selection does not include direct hierarchy, like Auto rig pro FK controls for example. Then each Temp IK chain will need to be created separatly.
Shape
It is possible to easily control the shape of the controls before and also after they are created, from the addon panel. When creating them it will also display them live while changing the different options.
Temp ctrls visualization can be also changed after they are created from the addon panel.
Shape Size
The size of the control. When using Original, then value of 1 will be the same size of the original rig custom shape.
Shape Type
Either use the original shape from the original selected bone, or select a new shape. The shapes are similiar to all the shapes that are displayed by empty objects. It's also possible to disbale shape when selecting 'bone' option.
Use selection filter to affect the shape and display on all the temp ctrl chains, or only the selected, or relative ctrl rig.
Frame Range
The frame range of the animation you want to bake into the new controls. There are 3 types of frame ranges the user can select
Scene Range
Will Bake on every frame through the whole scene frame range.
Custom Range
The user can decide manually on which frames he wants to bake. When using Custom Frame range, there will two keyframes automatically created on the On / Off Switch property of Temp Ctrls.
Keyframes Range
Bakes to the frame range of the original keyframes, it takes the frame range from each Fcurve. This is also part of smartbake.
Include All Layers
This option is relevant only for Keyframes range and smartbake. It takes all the keyframes from all the nla strips / anim layers of the original rig, if it's turned off it will use the keyframes only from your current action / layer.
Smartbake
Smartbake works only with Keyframe Range. It keeps the original keyframes count and position from the original bones, instead of baking and creating keyframes on every frame. Smartbake will also recalculate the handles between the keyframes, trying to match the values inbetween
Smart Bake for Temp IK
since the ik control and ik pole are not connected directly to a bone, smartbake will use the overall keyframes from the selected original bones, and apply all those keyframes to the IK ctrls
Rotation Mode
Select either to preserve your current rotation order, or to use a different one. You can always convert it later also using the convert rotation tool.
World Space Orientation
This creates a duplicate of the IK ctrl bone but in world space orientation. Z will always go up in world space in the graph editor. When Turned off than the ctrl bone will get the orientation of the original selected bone. It is recommended to leave it turned on. Pole targets will always be in world space orientation.
Add Extra Child Ctrls
adds an extra controller as a child of the Temporary controls. This gives an extra layered control over the temp controls baked animation. the original controls are eventually constrained to the child controls
Add Root Ctrl
Adding an extra root bone for Temp IK chain. It can be based on an object position or another bone. When using a bone the parent control will also bake the animation from the sampled bone. If no bone nor object is selected, then the parent will be added at the 3D cursor position. If a root bone was already created by other chains, and exist inside the temp rig, then it will use the existing one.