You should not.
Euthanasia is a gift that we give to our pet's whom are suffering and in need of a fast, painless death administered with dignity and respect for the life that is being extinguished.
Other than deliverance of Euthanasia solution by a trained veterinary professional, I do not personally believe there is a safe, humane, nonpainful alternative that could possibly be administered at home by an owner. Anything that I can think of, only brings to mind images of fear, suffering, panic and pain that your pet would ultimately experience in their last moments here on Earth.
You should consider finding a veterinarian in your area who will do house calls. IF you are hesitant to take your pet into the vet because you don't want to stress him/her, than an at home euthanasia is a perfect answer to appease your fears. Many vets are very understanding of your personal needs for euthanasia of your pet, and will do all they can to accomodate you and make your pet's passing as easy and painless as possible.
I hope you will strongly consider seeking professional assistance in this matter.