I find it easier to lay on my side and do it truthefully relaxes my glute med nicely

Yeah. No major veins or nerves, easy to reach so u can use both hands. I read somewhere that it can even take 5ml gear, never tried though.
What I do is just stand sideway in front of the mirror and flex my bottom.
Between the hip bone and the top of the tight bone there is an upside down triangle.
Locate the thickiest part of it, that's your injection spot.
It's called gluteus medius as well.
http://smart-nurse.blogspot.com/2011/06/locating-im-injection-sites.html

the bigger square not the smaller one

http://tnation.t-nation.com/forum_images/auto/r/350x0/f/e//fe833-erase_a...

This is pretty much how I do it -

This is how I locate my site: I do the injection standing up in front of my mirror. I turn to the side so I can visulize the site in the mirror as well. I then find the greater trochanter (this is the top of your femur that inserts into the hip - you can find it easily by feeling around as you lift your leg up and down a bit). Once you've located that, just find the front of your pelvis on that side and follow the ridge (iliac crest) to the back. you can use your hand to guide imaginary lines that go from the two ends of the pelvis to the greater trochanter - an upside down triangle. Once you have an imaginary triangle traced find the middle. Push down in the area to ensure it is soft and not bony. If it is soft you can inject, so swab the area with alchohol, prepare your needle - I have used as small as insulin needles (I'm lean) to as large as 22 gauge and as long as 1" 1/2.

I've been looking into it. Not to sure I have the right site though. The only images I can find show it from a second persons pov. I can't find anything on how to DIY.
Wow! Just saw the date of the op lol.