Hope this saves someone some time:
Pounds to kg: {formtext: name=pounds} lb or {=pounds/2.205} kg
Feet and inches to cm: {formtext: name=feet; cols=5}ft {formtext: name=inches; cols=6}in or {=((feet*12)+inches)*2.54} cm
Fahrenheit to Celsius: {formtext: name=Fahrenheit; cols=10}F or {=(Fahrenheit-32)/1.8; format=,.2f}Celsius