Please explain what a deb file does?
To be exact, it decompresses in the root directory and places files depending on the deb itself.
What is an .ipa? An ipa is an application archive which installs directly.
if you just want to do what the link you sent does, there is no point in MAKING a deb for that. Its only a copy/paste job. If you want to make a tweak or so WITH preferences, then you CAN NOT USE THIS METHOD. For eg, a nojb ipa to a deb patcher cannot be done from what you posted.
Moreover, speaking of my arrogance, I have good reason to doubt your expertise, considering you are REALLY ambiguous about what you want to do. All you said is convert ipa to deb, which in itself there is no point.
Is there ANY OTHER reason you need to do that? Maybe making something like a cydia app which requires root?
Also, what you posted in exact terms is :
1) Make a control file in DEBIAN folder
2) Make a directory to where you want to install the app from root.
3) Compile it
In essence, thats exactly what we do with theos and if you knew that, you wouldnt need anyones help