How to install background on smaller tank

[joe-ejs]

Hello. I just set up a smaller tank in my office which is a standard 29gl. I want to install a black background that I purchased which is the typical plastic/mylar coating. I did this years ago using vegetable oil and squeezed out the bubbles with credit card. Is this still the best method? Tank is running so I can't paint the back glass. Just want to go with the easy method.

Any suggestions is appreciated.
Thanks

 

[joe-ejs]

bump...any suggestions on how to do this?