Philosophy: How we should practice the concept "treat guest as God" in a practical modern way?

I heard the quote in ISKCON many years ago and found the Taittiriya_Upanishad as probable source.
http://en.wikipedia.org/wiki/Taittiriya_Upanishad

While we do not take instruction of Taittirya Upanisad literary it states:

Do not neglect your duties to the devas and the Manes. Treat your mother as if she were a demigod Treat your father as if he were a demigod. Treat your teacher as if he were a visiting demigod. Treat your guest as if he were a visiting demigod (atithi-devo bhava). Whatever deeds are faultless, these are to be performed—not others. Whatever good works have been performed by us, those should be performed by you—not others.

Taittiriya Upanisad (1.11.2)

Another quote from Bhaktivinode Thakur

A guest is a person of this kind. O human beings! Did you understand whether honoring of guests is your duty or not? It is the duty of every human being to help the shelterless people according to his capacity. Just as you are made of blood and flesh so are the guests and poor people. Their feeling of happiness and distress is similar that of yours. They possess the same consciousness that is present in you. Do they not belong to your class? Is it your duty to bring constant happiness and prosperity only to your family members? Is it your duty to mitigate your own hunger and thirst like the birds and beasts? Has the well-wishing Supreme Lord not given you more intelligence, knowledge, and power than them? Then why do you display cruelty like them? It is a duty of every householder to serve the guest who has no shelter and help the fallen and poor according to their capacity. One cannot estimate how many people take shelter of the householders for help due to so many reasons. To help the poor, fallen, and guests according to one’s ability is the desire of the auspicious creator. If you exhibit indifference in such activities, then you will certainly incur sin. The thoughtful sages have ascertained this as the duty of the householder. If a householder fails to execute these duties, he commits grave sin. Long long ago honoring of guests was very popular in this country. A householder should consider this as an act of piety and try his best to serve the guests. If you act after careful consideration then you can easily maintain your family and serve the guest with your earned wealth. But alas ! what a subject matter for repentance. Today this great vow is often neglected in the Hindu society. Many People say that serving of guest is a costly affair, therefore it is not possible for all the householders. If all or most of the householder take up this great work then serving the guests will not require heavy expenditure.

Chapter 9 of BVT's Devdas (1910)

The main point is the consciousness, that the Supreme Lord is seated in their heart and is watching everything and do it as a service to Sri Guru and Sri Krishna.