WEP Encryption for WiFI Hotspot in KitKat
Since WEP encryption is very, very insecure it was replaced by WPA/2. 
Creating WEP encrypted WiFi networks today is very risky because it can be hacked within seconds.
So the answer is you can't create a WEP encrypted WiFi Hotspot with Android.

BTW:
An app can only use hotspot features the device is supporting. And because the newer Androids don't support WEP there is no way for the apps to create hotspots with WEP.