You can find a link to the recipe for low carb graham crackers here. I just ground them down in a food processor. It's helpful to grind them a little more finely than you think you might need to. We are only using water to adhere the crust to the rim, and it will stick better if the crackers are a little more completely ground up.
Swerve (and honestly erythritol blends of all kinds) have a reputation for being a little bit resistant to dissolving, which is why I call for the Confectioners-Style version of the sweetener here. There is not a lot of time for the sweetener to completely dissolve in the preparation of the drink, so we use it more finely ground to help the process along. If you are using granular or generic erythritol, you might want to consider grinding it up more finely in a spice grinder.