Is it safe? The short answer is no. Is it doable? Sure. This is a form of a speedball, (coc+opi). If you're looking for pain relief from the cocaine, you'll be disappointed, it only numbs your face, mouth, and throat.
I'll never suggest this practice, but it's not an automatic death warrant. I will say if you do decide to do it, take half the amount of codeine and cocaine that you normally take.