Nobody uses cheats in EB. It satisfies even less than losing. You don't need a big army to fight the Seleukids. You can win as long as you keep your somatophylakes together in the first few turns as a heavy cavalry arm. Invest in lots and lots of shuban fradakshana, they are the force multiplier. 6 units in your army will chew up anything the Seleukids can throw at you within the first 10 years or more. I managed to conquer all the way to Sardis with pantodapoi phalangitai and shuban fradakshana with Mada asabara, so there you go. The trick is to go for the AS as soon as you see them moving towards your borders. If one crosses it, attack and don't wait until it attacks you.