No. This is not possible. the voltages and the messaging protocol for USB serial ports are extremely different from a RS232 serial port. The two are simply not compatible. You need to purchase a USB to Serial Adapter that will interface and translate between the two protocols.
Would it be possible for me to create an "All in One" USB port based EAS Serial cable? Short answer is yes. It is technically possible to create a device that plugs into a USB port and then sends signals out using a RS232 protocol.
Long answer is no, why would I create that. The increase in cost would be significantly greater than simply purchasing a "USB To Serial Adapter" and pairing it with a RS232 EAS Serial cable. In the end we would end up with a device that costs somewhere around 80-100 USD. You can easily purchase an inexpensive "USB To Serial Adapter" that can be as little as 6 USD to purchase. It is simply not cost effective for me to design, manufacturer, stock and sell a product that has to compete with a 6 USD alternative.