It's easy actually. I hold one pick between my thumb and 1st finger and the other between my first finger and pointer. To get the distance correct you can tilt your hand slightly so that one of the picks (the lower one)is slightly closer to the bridge than the upper pick. If you can do a tremolo with one pick you can, with a little more practice do it with two. I'd record you a sound file but I haven't got that facility on my computer as yet.