CustomGame.LoadPreset(int preset);
Syntax
public void LoadPreset(
    int preset
)

preset
Preset to load.
Type: int

Loads a preset saved in Overwatch, 0 being the first saved preset.

using System;
using CustomGameOW;

...

static void Main(string[] args)
{
    CustomGame cg = new CustomGame();
    cg.LoadPreset(0); // Loads the first saved preset.
}