How does someone get to the judge to sigh the waiver of extradition while sitting in a county jail?

He needs to immediately contact his public defender.  If his public defender is ineffective, think about possibly consulting with a private criminal defense attorney at www.attorneypages.com.

In terms of waiting, one week doesn't seem all too long.  Reasonable delays do occur.

548.243. In any criminal proceeding wherein a court in this state has issued a warrant for the arrest of a person and that person was arrested in any other state, territory, or possession of the United States and that person waives extradition and consents to return to this state, the sheriff of the county where the warrant was issued may contract with an agent for the return of such person to this state, or the sheriff or his deputy may return such person to this state. All necessary expenses which would be paid by the state if there had been extradition, incurred by the sheriff, his deputy or an authorized agent in returning the person shall be paid to the sheriff by the state regardless of the ultimate disposition of the criminal proceedings. Such costs after such payment shall be taxed against the person and recovered by the entity paying the same, unless the person is acquitted of the criminal offense charged.

548.260. 1. Any person arrested in this state charged with having committed any crime in another state or alleged to have escaped from confinement, or broken the terms of his bail, probation or parole may waive the issuance and service of the warrant provided for in sections 548.071 and 548.081 and all other procedure incidental to extradition proceedings, by executing or subscribing in the presence of a judge of any court of record within this state a writing which states that he consents to return to the demanding state; provided, however, that before such waiver shall be executed or subscribed by such person it shall be the duty of such judge to inform such person of his rights to the issuance or service of a warrant of extradition and to obtain a writ of habeas corpus as provided in section 548.101.

2. If and when such consent has been duly executed it shall forthwith be forwarded to the office of the governor of this state and filed therein. The judge shall direct the officer having such person in custody to deliver forthwith such person to the duly accredited agent or agents of the demanding state, and shall deliver or cause to be delivered to such agent or agents a copy of such consent; provided, however, that nothing in this section shall be deemed to limit the rights of the accused person to return voluntarily and without formality to the demanding state, nor shall this waiver procedure be deemed to be an exclusive procedure or to limit the powers, rights or duties of the officers of the demanding state or of this state.