As it turned out it was not that hard. I had some cheap USB-Serial adapters and I know that these cable inside have a USB to TTL serial chip then a second chip to step the voltages upto the RS232 standards. 

This is the adapter with the moldered casing removed. If you ever have to remove a moldered casing, remove the edges first and top can be peeled up without damaging any components.

Now that I can see that it has a PL-2303HX chip I can start looking for the datasheet to find the pins that I need.  

Now rather then solder directly to the chip I traced the pins until they were more exposed. I was in luck, they both connected to diodes which made a great spot to attach my wires.  

Completed

In total I attached 4 wires, RX, TX, GND and 5V. 

Connecting the RX/TX wires to the USnooBie TX/RX pins (D1,D0) I was able to create sketches that use Serial.println now for debugging.