Yep, certainly can.
Easy way, using the Draw GUI event.
But if you need it in the scene itself, use the matrix functions to scale and position.
Quick tip. Scale the sprite down so you can initially see it, otherwise it will be massive in comparison. In 3D space you might have a 1x1x1 cube model as an example. If you try to draw a sprite, it might have dimensions of 128px x 128px. That same 128px is its size in 3D space. When you compare that to your model, it's massive! So first thing you want to do is scale it down to be proportionate in the 3D world.
Just thought I'd mention that, because the first time you try it you might just get a mass off blurry pixels in your face when you draw the sprite. If you do, then that's a good thing, you are on the right track, just gotta then scale it down.