I have found a way to add custom icons to the draw tool. This is for when you draw point features. It was actually easier then I thought after a lot of digging.
[app number]\jimu.js\dijit\SymbolsInfo - add a new file like 11.json with the following: (you will not be disappointed)
[
{
"height":24,
"width":24,
"xoffset":0,
"yoffset":0,
"name":"Autobot",
"contentType":"image/png",
"type":"esriPMS",
"angle":0,
"url":"http://img3.wikia.nocookie.net/__cb20140626131150/transformers-legends/images/6/6b/Autobot_symbol.png"
},
{
"height":24,
"width":24,
"xoffset":0,
"yoffset":0,
"name":"Iron Man",
"contentType":"image/png",
"type":"esriPMS",
"angle":0,
"url":"http://www.veryicon.com/icon/png/Movie%20%26%20TV/Ironman/Ironman%20M%20III.png