From the author's README on Thunderstore

fan made mod for skate that adds Roxas's skateboard from Kingdom Hearts II

Requirements

skate. (Steam)
ReSkate / ReSkate Launcher

Installation

Thunderstore / Mod Manager

Install Roxas Board through your Thunderstore-compatible mod manager, then launch the game through ReSkate.

Manual

Close the game.
Open your skate. installation folder.
Open or create the Mods folder.
Extract this package so the files in this archive are directly inside: Mods/RoxasBoard/
Start the game through ReSkateLauncher.exe.

The package intentionally contains the native ReSkate files (layout.toc, Win32, etc.) at the mod root.

Notes

This is a native ReSkate mod and does not use BepInEx.
ReSkate mods are tied to the supported game build. If skate. updates, this mod may need to be rebuilt for the new build.
If the mod does not appear or load, check the ReSkate log for the reason it was excluded.

Credits

Mod: Krismaws
Board: Roxas's skateboard from Kingdom Hearts II / associated rights holders.
Built/packaged for ReSkate.

This is an unofficial fan-made mod and is not affiliated with or endorsed by the rights holders.

Install RoxasBoard

You need ReSkate and your own copy of skate. on Steam.

Open ReSkateLauncher.exe and go to MODS.
Search for RoxasBoard and click install. The launcher also installs anything it depends on.
Press PLAY. In game, the MODS tab of the ReSkate menu (Insert) turns it on and off.

Or install it by hand: download the .zip and drop it on the launcher window, or unzip it into its own folder in Mods\ beside Skate.exe.

Maps show up in the ReSkate menu's level list. To join a server running a custom map, you need the same map installed. If the game won't load after installing, see known issues.

skatemods doesn't host or review this mod. The download comes straight from Thunderstore. Only install mods you trust, because scripts can run code.