You must have TW framework in the ROM, as the TW launcher relies on more than just the launcher apk to properly run. Slim, as well as all the other CM/AOSP ROMs do not have this framework. This is fairly common knowledge, search would have given you several thousand answers to this question. Whole point of Slim and the like is to NOT have TW.
Sent from my GT-I9505 using XDA Premium HD app
Loki'd AT&T Samsung Galaxy S IV
More than likely, running GoldenEye
Rooted with Motochopper
Samsung Galaxy Note 10.1