Hello from Centennial Colorado

Been brewing for around 7 years'ish.  Started with extract, got a turkey fryer for the larger kettle, now I use a Megapot and all grain in a cooler and kegging in two tap kegerator.  Happy with where I am and have made some killer and not-so-killer beers.  Favorite beer to brew is a blood orange IPA. Reading more and more and continually learning.  Just put my first recipe in Beersmith and already have a question! 

Instructions say to do a protein rest and then heat to 152F then heat to 168 for mashout.  How do I do that in a plastic cooler without adding hot water???

There are only three ways of heating up your wort in a plastic cooler.  The first is to add your water in separate additions which will raise the temperature with each addition.  You will need to determine volume additions and temperature through the program to achieve your desired rest target.  If you do this, aim a few degrees higher than the temperature determined by the program to account for cooling losses during the rest.

The second is to decoct your mash which is taking out some of the grains, heating to mash temperature for a short while and then to boil.  Add this back in to raise the temperature of the mash to the next rest level.  You can do the same for the mash out temperature (168F). 

Alternatively, take out some of the mash liquor and heat it up before adding it back in.  This gets tricky, since you don't want to heat up the wort too high and too fast and denature the enzymes before they can convert the starches. You can take out about a third at a time, bring to boiling slowly and then add in what you need to raise the temperature to the next target.

My recommendation would be to plan on mashing in at your target mash temperature (152F), and skip the protein rest.  Unless you are using chit malt or some other low modified malt, it is not needed.  Then you can heat your sparge water up to about 176F and use that to bring your temperature up to mash out.  If you are batch sparging, you can just skip the mash out and start heating your drained wort up to boil which will do the same thing as a mash out.