Wouldn't a cold water washer remove it? Or a hot turbo (old bricks)
You may struggle with just cold water, turbo's are usually temp rated so cant run them hot hot ?
We used to remove posters on a regular basis for a local bank, method we used was hot box at full temp std nozzle ...same setup for gum removal. Try and remove as much of the 'face' of the poster before washing as it goes everywhere
If I was quoting now I think it would be easier to use 8" mozzy at full temp with recovery to save the mess, that way the mess is contained in the vac.
Just noticed how old original post was ! Thats a hell of a wait for a PO