from pymel.core import *

sel = selected()[0]
cam = PyNode( 'persp1' )
parent( sel, cam, a=1 )
bbcoord = xform( sel, q=1, os=1, bb=1 )

near = -bbcoord[5]
far = -bbcoord[2]

cam.setClippingPlanes( 1 )
cam.setFarClipPlane( far )
cam.setNearClipPlane( near )

parent( sel, w=1 )