How can you create an application LiberKey?

If you are talking about how to portabilize any software, know that LiberKey is not that kind of miraculous software.

But if you are talking about how to transform an portable app to a LiberKey app, I think the solution is following:
1. Organize folder structure from your portable software to that:
Software name
|-App: Put inside that all program files
|-Data: Put inside that all user data files

2. Portabilize your software using http://wiki.liberkey.com/liberkey_portabilizer , creating *LKL.exe file (I dont know how to do it yet)

3. Submit it to be added to LiberKey catalog, in this forum.

Keep in mind that softwares have licenses and some of them should not be delivered freely.

No need to create a <app>LKL.exe, using file association with Liberkey Portabilizer is enough.
You just have to double click on <app>.lpf to start the application using LiberkeyPortabilizer

Check (my) examples of submitted applications (french posts):
John's Background Switcher (scripted with LiberkeyPortabilizer)
Window Hide Tool (scripted with LiberkeyPortabilizer)