Insert a pause-gcode (M226) just before the last layers. Then, when the printer pauses, insert your RC04 into the holder. Resume the print while holding the RC04 in place. After the print is done, very carefully remove the RC04. This thing is very tall. Make sure your Z-axis runs smoothly on all of it's length. Not just the first 5-10 centimeters. If you encounter skipping due to reaching seldom used parts of your Z-axis, you can later repair the object with a bit of hot glue (like I did).