It is not often a contending team adds a former two-time NBA scoring champion less than a week before the start of the playoffs. That is exactly what the Spurs did eight days ago, when they signed 33-year-old swingman Tracy McGrady, recently of the Chinese Basketball Association. It could still be a while before McGrady makes his Spurs debut. Inactive for the Spurs’ 91-79 victory over the Lakers in Game 1, McGrady is all but certain to spend Game 2 on Wednesday night in street clothes as well. “We’re going real slow,” coach Gregg Popovich said. “We wanted to have another body just as an insurance policy. You don’t know what’s going to happen during a playoff series. We wanted to add someone.” Having arrived in San Antonio two months after his final game in China, McGrady has spent the past eight days working back into basketball condition and familiarizing himself with the Spurs’ playbook. “With Tracy, he’s a pro,” Popovich said. “He knows how to play. It’s just a matter of getting him in shape, and if the situation arises where we want to look to him, he will be ready to do what he does.”