how would i go about adding tile / tilemap inputs to a custom block?
You can do it like setCurrentTilemap() block do:
//% tilemap.shadow=tiles_tilemap_editor
in tilemap.ts
/**
* Sets the given tilemap to be the current active tilemap in the game
*
* @param tilemap The tilemap to set as the current tilemap
*/
//% blockId=set_current_tilemap block="set tilemap to $tilemap"
//% weight=201 blockGap=8
//% tilemap.shadow=tiles_tilemap_editor
//% blockNamespace="scene" group="Tilemaps" duplicateShadowOnDrag
//% help=tiles/set-current-tilemap
export function setCurrentTilemap(tilemap: TileMapData) {
...
}