NASA and other space agencies formally -- if grudgingly -- agreed Tuesday to grant Tito an "exemption" to normal astronaut selection procedure, effectively giving the U.S. millionaire a green light to become the first private citizen to pay his own ticket to space.

But Tito's stopover will cause a work slowdown prepping the huge orbiting complex, particularly in checking out the newly installed robotic arm.

Shortly thereafter, the Task Force on International Space Station Operational Readiness, an independent group chaired by former Gemini, Apollo and Apollo-Soyuz Test Project astronaut Thomas Stafford, spelled out a number of provisos for Tito in the form of a waiver.

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To further reduce risk, Stafford said, "it should be made clear to Mr. Tito that his activities are limited to the Russian modules, due to his lack of adequate training on the U.S. modules."

That situation will exist unless Tito is escorted by an Expedition To crew member for the identification of emergency equipment and any required safety briefing, he said.

Additionally, Stafford said it appears prudent that Mr. Tito should sleep in his designed Soyuz return vehicle in case an emergency should occur during his sleep cycle.

Finally, Stafford said that Rosaviacosmos the Russian Aviation and Space Agency -- must guarantee to all of the ISS partners that it is fully liable for the flying of Mr. Tito, and that in the future, "this type of unilateral decision will never happen again."

Paying some $18 million for the ride, Tito will blast off Saturday with two cosmonaut crewmates, mission commander Talgat Musabayev and flight engineer Yuri Baturin. The trio will link up with the ISS and its three-person live-in crew the following day.

The hop to the ISS involves a swap-out of Soyuz craft -- old for new. A Soyuz capsule is continuously docked with ISS, ready as a crew emergency-escape vehicle in the case a contingency arises on the station.

Tito will spend nearly a week aboard the orbiting facility, then return back to Russia with his two Soyuz shipmates.

In a letter to Joseph Rothenberg, NASA associate administrator for spaceflight, Stafford said he was disappointed to learn that Rosaviacosmos had not followed earlier recommendations of the Task Force-Advisory Expert Council Joint Commission.

"It is unfortunate that NASA must now take risk-mitigating actions that will affect the productivity of the ISS Expedition Two crew," Stafford said. Work on the Canadian-built robot arm, a treadmill and a crew health and checkout system is being put on hold while Tito is onboard. That situation, however, might change depending on how well Tito fits into day-to-day crew operations.

The Soyuz taxi crew will receive twice the amount of time normally allotted for on-orbit safety briefings, Stafford said. The Expedition Two crew commander will determine, based on his real-time assessment, what is the safest for the crew to achieve in working on the ISS.

"While these actions may slow the progress toward ISS assembly completion, a long journey awaits us, and safety of the crew and the ISS cannot be compromised," Stafford said.

Titos go-ahead means the space tourist has risen above the roar of rhetoric that persisted for months between ISS partners -- NASA, European, Japanese and Canadian space agencies questioning Titos "non-professional" flight status, but running up against Russias steadfast position of flying the multimillionaire.

Tito has undergone eight months of cosmonaut training, with Russian space officials contending he is fit and ready for the flight to the ISS.

The 60-year-old financier originally plunked down his money for a liftoff to the Russian Mir space station. But that round-trip ticket was cancelled when Russia purposely deorbited the aging complex last month, crashing it into a huge stretch of south Pacific waters.

For now, Tito is all dressed up and has somewhere to go.

"I think theres been a lot of foot-dragging on NASAs part," said Bob Haltermann, executive director of the Space Transportation Associations Space Travel and Tourism Division.

"I think people realize that for the most part, NASA has been an impediment in this process. We hope that some day they come around to the fact that other people want to, and deserve to go into space other than just their own astronauts. They should have programs to accommodate them," Haltermann told SPACE.com.