Title says it all really. I want my player to start with items already in their inventory, how would I do that?

When you're editing an object, you can use the "move" button to change where it starts. Just put it in the player object.

Or...
start the player in a room where the starting objects are.
have a exit to the start of the game...
To make it interesting, they can't take everything, but need to select what they start with.
Some will help, and some will not.