I just tried yesterday to unlock the 1.1.2 OTB and I did the following:
1. Activate and Downgrade to 1.1.1 (Done two months ago)
2. Donwload Ziphone 2.4b and execute '''FULL AUTOMATIC''' batch file
3. Donwload 1.1.3 file and activate it with Itunes 7.6 (lastest one) upgrade+Shift
4. Run Ziphone 2.4b command as follow. Under DOS write ''ziphone -j -a''.
It Works OK.
For sure if you have already an 1.1.2 activated, dont make a downgrade just exucute step 2 and the rest.