I think it depends what interface you're using. I have the c++
interface, and there is a ck2cti.exe file in my Cantera\bin folder.
However, the python script should do what you're looking for.
I
assume you have python installed (more or less needed for Cantera), and
added the folder containing the python exe to your path (if not and on
windows, see here:
http://www.computerhope.com/issues/ch000549.htm)
In command line navigate to the folder with the ck2cti.py file
Then run it something like (assuming you have python on your path):
python ck2cti.py --input=chem.inp --thermo=thermo.dat --transport=tran.dat
where transport is optional (there's also an output and phase id inputs you can use to change the name of the .cti file created and the name of the phase created respectively)
I
find it easiest to copy all my mechanism files to the bin directory, so
I don't have to specify paths, and then move the .cti to wherever.