In real life we went 5/6 in stolen bases for an 83.33% success rate.
His WIS speed is 53.

I'm planning to set him to 0 base stealing but I am curious if anyone knows how the sim treats players like him who have high success rates with 5-10 attempts.  Does he get any boost to stealing success or is he the same as a 53 speed guy that goes 0/1 or 1/2?

No, you'd need more than 6 attempts to be treated like an elite guy. And I think speed is a factor too. Even Chase Utley in his 23/23 season doesn't get treated that well because his SBA/100SBO is so low and he's not that fast.

I believe speed enters into the SB calculation, meaning you should set him at 2 or 3 and not count on much.   even if you set him at 5 and batted him leadoff, which I know you won't, he wouldn't steal too much. I  would be more worried about his GIDP line....