Your rectum or "drt a-hole" is a naturally moist environment. You should have made a solution first. Mix the meth with water then squirt using an oral syringe or what have you.
Essentially, this process will occur in your rectum anyway. The mucous in your rectum will cause the meth to solute and then be absorbed through those membranes.
It is just a less efficient way of getting this done but it should work nonetheless.