If I were to adapt the activity of Baseball for a non-ambulatory person with hemiplegia on the left side, to participate in an integrated program, I would have to consider the 4 categories of modifications to have a good plan.
They are: Procedural/Operational which focuses on rules of the game, Evironmental deals with where the game will be played, Equipment focuses on adaptations to playing equipment and Human Intervention involves human contact, praise and instruction.
Focusing on Procedural/Operational modification, I may change a few rules. I may have a pinch hitter for the runner who will run from home plate with the batter to 1st base and then take over from there or have the batter have a few seconds of lead time before the ball can be thrown after their hit. I will also allow the batter to either use a batting tee instead of having the ball pitched to them or they can have the ball pitched to them at a low speed, whatever they are most comfortable with.
On defense I will allow the player to be teamed up with another player to assist them while playing their position.
For environmental modifications, I would have the game played on a hard surface, such as concrete or blacktop, so the player can move as easily as possible. And have flat running bases so they can actually tag the base. I would also shorten the playing field/area to accommodate the player but still allow everyone else to enjoy the game as well.
One of the most important modifications that can be made is to the equipment. They way I would modify the equipment used is to have the player use a lighter but bigger (wider and longer) bat to help hit the ball better. The bat may also have a brace, which goes from the handle and straps on to the forearm so they can swing and control the bat better. I will also use a brighter color and slightly bigger ball so the player can connect better for the swing.
For Human Intervention, I will have a 'buddy partner' for the player to help with anything necessary, they would be there as an aid for the disabled player. For instance they will help the player run their bases on offense and help them to scramble for the ball on defense. This 'buddy partner' will also help the child with proper game instruction and tell them what they may need to change in order to play better.
I think these modifications would help someone with left-sided hemiplegia play in an integrated game of baseball where everyone can enjoy. In order to think of certain adaptations for someone with a disability to play any particular game, I learned that you have to be very creative and look at things from not only your perspective but from theirs also.