I just had to redo my fuel system, and had to re-learn how to do that . What worked for me was a TIGHT wrap of vinyl electrical tape, at least three times around, a thin cutoff wheel (1/32) , wrap the tape over your mark, and cut through the tape. I even tried to leave the tape in place has i inserted the line in the fitting, as it would peal off as it was inserted.
Im sure there are better ways, techniques and tools, but thats how i did it.
Edit: thats what i did with braided rubber line. I have come to the point that i like to use teflon line, and i let the local line specialist assemble for me, i dont have tools or technique for teflon.