Using regular BC pills as emergency BC?? How??

I have a pack of regular birth control pills. I read, somewhere, awhile pay for, that if you didn't have access to emergency birth control, afterwards you could somehow take pills from a regular BC pack ~ near was approaching some way to combine them, or a dependable number of doses or something like that..and I can't remember.
But I KNOW it can be done.
Please lend a hand?! :) Plan B is available over the counter, you could just buy that. There are persuaded types of birthcontrol that can be used as EC, but they are monophasic, If you take a triphasic birthcontrol resembling Ortho-Tri-Cyclen then this would not work. Just progress buy Plan B if you need EC and amass your regular BC.
You go to the store and buy a condom.