Urgh, internal t47 cups ones can be a pain to get to torque (or remove the damn things later).
As for the type of tool, count the notches and measure the outer diameter. These are the numbers you're looking for in the tool (obvious as it sounds, but yea, that's it). However, there are bb nuts where one side fits multiple different types of bb cups - basically multiple interface types stacked like a staircase from bigger to smaller. These are no good unless the interface you need is the outermost (even then, I'd take rather not use these), so look out for that.
Now, for the tricky part. With that kind of bb cup, you have maybe 2 mm depth for engagement between bb cup and tool. This is, like, nothing when trying to apply 30-40 Nm with a 30 cm lever. Therefore:
1) If there is, I'd get a steel nut - I am saying this as most of these tools are the same softish aluminium as the bb cups which means that even with the slightest of slips both sides will give and you can easily round both the cup and the tool in a flash (ask me how I know). With a harder tool (insert "tool" joke here), you have just ever-so-slightly better odds.
2) If the nut's open end is even slightly rounded or chamfered on the inside (which is often the case), I'd grind it flat to give the teeth proper edges. I hope that makes sense to you(?)
3) Grease threads!
4) Secure the frame well (it should not be able to move anywhere) and press the tool firmly onto the cup when applying force. Alternatively, there are contraptions to secure bb tools to the cup/shell (basically a threaded rod with a thrust bearing and some bits), but I have yet to see one for t47.
Now, this might sound way over the top, I mean, how hard can it be, right ...
