I haven't tried to use a clearomizer and would worry about contamination of the e-liquid from the sealant.
I heard of people using steel carto's after cutting a slit or punching a hole in each side. I have not tried this.
The MAP tank works awesome the way it was designed to be used, using the steel CE2's.
Edit to add;
I also heard of being able to press a steel tube that was left over after you cut a steel CE2 and pressing that on a clearo and recutting it. However, I have not tried this either.