Never did it with a SLC, but have used it with many 5's. It's been awhile, but if I remember correctly the scale is 1/4 rack, with two input words, and two output words. You need to acquire the manual on the scale rio module, one of the input words is the weight, and the other one contains status bits. The output word can be manipulated at the bit level to reset, tare etc....
No BTW or BTR required, the data will be in the I/O image table, you just need to manual mentioned above to decipher what's located where. Unless Metler-Toledo has changed the way they do things, you will have to get the manual from you local rep. you cannot download it, and it's not on the standard CD that ships with the scale. Which scale module are you interfacing with, the Jaguar?