To my knowledge, McMillan does not offer their stocks with KMW hardware installed, and their McM integral adjustment types have significantly different hardware and different inletting.
If ordering a new McM and you intend to send it to KMW for their installation, you will need to order your stock with full fill, KMW inletting, and (cheekrest) hardware delete.
Then you can send it to KMW for their hardware installation after you get it from McM.
But if your McM stock is already made, you will need to contact stockdoc about it and see if he can install the hardware on the stock you already have.
Don't know if Manners will fit one after the stock is made (my Manners T4A came with the KMW hardware).