In a dry skillet, toast cumin seeds until fragrant, then transfer to a mortar & pestle or a spice grinder. Repeat separately with the whole cloves if using, and with the whole allspice if using. Grind the toasted spices into a fine powder.
Mix in the remaining ingredients (including ground cloves and allspice if using). Store in an airtight container in a cool place. Will keep in the pantry or fridge for up to 3 months or so.
WHOLE VS GROUND SPICES: You'll get the best flavor with whole spices. Bonus - the whole spices that are the components in this Jamaican jerk also stay fresher for longer than their ground counterparts. However, ground spices will work if that meets your needs better. I've tested this recipe both ways.