A "found" box will not operate without being authorized on the system. it must be added to the users account to operate and authorize the encrypted channels. All configuration, decryption and channel maping is sent down from the headend once the box is authorized. There is nothing to configure on the box itself.
That said, that is the oldest digital std def box out there, and most have been called in to be replaced with an updated box. It has so little memory that it can barely operate and will not work with the new features, and the channel guide barely will show one or two days.
If the box was found, calling into Comcast will not get it activated since it is not leased from Comcast or is "lost" equipment that belongs to some US cable company.
