I am also looking into this problem and think the best solution is to
cut the ATP plug off and re-wire with an RJ45.
However, the cable being used may not be suitable for this solution.
Another way to convert would be to use RJ45 patch cables with a RJ45 to
D25 (or D9) pin adaptor (approx #3-4) and replace the ATP connector with
a D25 plug. The original cable should be suitable for a D25 plug.