I will bend the rules a bit because as per rules we are not supposed to talk about customizing windows (even PE setups) and give a quick answer assuming you know the basics about how to handle ADK, and IMaGes, etc.
Dism will do the trick for you by typing
DISM.exe /image:c:\TEMP_IMG /Add-Driver /driver:c:\drivers /recurse /FORCEUNSIGNED
As you see you need to take care of a few things before you issue the command
1. Set the right directory of the image in the "/image:c:\TEMP_IMG"
2. Set the right directory in the /driver:c:\drivers
3. /recurse when you want to add multiple drivers in the same folder. Note here that some drivers have support from multiple devices and might inflate your image.
4. /FORCEUNSIGNED In case your drivers are not signed.
Make sure the drivers are unpacked. What that means is you need them in a form that uses the .inf file and not a .exe file. Google for more info.
You can find plenty of info on how to create a window PE image and more details on DISM.
I will close this and if anything else is needed relating to the topic, contact a mod/admin.
