I have figured out the technique to boof it. When standing, one must apply a sharp angle of the syringe diagonally upward, toward the rectum, and not apply any more pressure than by merely holding the syringe. Once you have located the rectum with the syringe, push the syringe as far as possible, without pushing the substance inside yet, just the whole syringe (you can use almost any syringe the needle of which you can remove, you don't need anything special) and then the light pressure on the button-thingie that pushes the substance will on its own inject the ket. All about minimal pressure and correct angling.
CTB shall commence shortly. Thank you all for your attention and advice.