How to change a players package ids and textures during playing (R15) ?

Code sample:

ORIGINAL_RightUpperLeg.MeshId = RightUpperLeg.MeshId
ORIGINAL_RightUpperLeg.TextureID = RightUpperLeg.TextureID
ORIGINAL_RightUpperLeg.Size = RightUpperLeg.Size

i have tried to change the players mesh id and texture id but it comes with an error.

Error: Unable to assign property MeshId. Script write access is restricted

I dont want the player to equip the whole package only a part of it .E.g the torso