You might get better responses if you posted this in techinque, but I may be able to help. The first thing you need to focus on is the left hand. The way I play and seems to me is the best way is to keep your pinky finger held down on the E string at all times when playing the harmonics, because you will need to jump back to it all the time. The harmonic above the 5th fret should be played with the index finger and the harmonic over the 7th fret should be played with the ring finger. This seems to me to be the best left hand technique. In terms of the right hand technique there is nothing that should be two difficult after practicing for awhile. To play the two harmonics together all you have to do is use both your index and middle fingers at the same time. The index playing the string lower in pitch (The D for the first harmonic) and the middle playing the string higher in pitch (the G). No special technique is required. Then for the C on the E string just play that with your index finger. I find it helps when fingering this with your right hand to keep your fingers in the proper position to pluck two strings at once at all times. After you play the first harmonic set and are going back to the E string to play the 8th fret with your index finger, keep your middle finger in relative position to your index finger so you can easily go back to playing two strings at once. I'm not too good with words so I'll attach a picture to explain better.