PreCaching Task Sequence on Client Machine

One of the most annoying things i've found about ConfigMgr is the inability to preload contents on the client - either by preloading the client cache, or any other method.
I have found a way to preload Task Sequence components, so you can run an OS deployment off a client machine, reducing network load and increasing the amount of machines you can potentially build at one time.
You will need TSENV2.EXE to do this, you can get this here - its the Advanced Task Sequence Environment tool - used to overwrite normally readonly TS Variables (those starting with_)

So the idea here is to override the TS variables pointing to network locations and redirect them to a local folder. The other part of this is ensuring your local content does not get removed by a format or wipe when the OS is applied.

Part 1 : Overriding content location

The content location is stored in the _SMSTSPackageID task sequence variable
To override this, use TSENV2 like so:
tsenv2.exe set _SMSTSPackageID =sNewLocation

For example:
tsenv2.exe set _SMSTSA0100012 = sC:\Cache\A0100012\

This points the package source locally. The lowercase s above is actually very important, and not a typo!

Part 2 : Protecting Cache folder

Obviously we want our cache folder to not be deleted or otherwise removed until the build has completed - there are a couple of ways of doing this.
Firstly you need to ensure your TS has no Format and Partition steps, as this will remove the cached packages.
1. Set the cache folder to be the Local State Store directory, this will ensure its protected
2. Add the cache folder to the protected folders list (this contains such folders as the Task Sequence local folder and the state store folder. This list is stored in the variable : _SMSTSProtectedPaths

You can choose the option that best suits you, I prefer the local state store method as its very easy (just set the OSDStateStore variable and you are done).
To use mthod 2, you will need a script that reads the _SMSTSProtectedPaths variable, and then uses TSENV2 to overwrite it with the existing content, plus the new folder.

Step 3 - Implementation
To use this method to build your machine locally, you need to do the following:
1. Copy the package content to the client machines (up to you how you want to do this, robocopy, usb, use sccm) As long as all the packages are in the same folder and clearly identified with the package ID it doesnt matter how they get there.
2. Create a script to override your TS variables to the new location. Do this by iterating through each _SMSTSblahblah variable in the TS Variables, then matching the package id to a cached subfolder in your cache location and finally overriding each variable.

I will try to get some sample code up if anyone is interested (drop me a comment). It's a very simple script - as mentioned above, just get your content to the computer, step through each _smsts variable, match it to existing content on the machine and override.
Hope this helps!
FYI - this was done on ConfigMgr 2007 , I havent tested to see if the same principles apply to ConfigMgr 2012.