The only slow presses gymnasts would do would be controled straight arm press handstands.
In fact, there's the forward roll out of handstand into straight arm straddle press... and do them like 10 in a row if you're really proficient. Crazy hard.
There's no use doing any other bent arm pressing besides assisted or free handstand pushups which should be done much like any other bodyweight movements... aka explosively in most cases.
Full HSPU you're better off working with parallettes against the wall