The fastest way to select a part in either the board or schematic is with the PCB open, then use the following:
(assumes you already have a valid reference to pcbdoc, the PCB document object)
dim refdes as string
dim comp as mgcpcb.component
refdes = "U1"
comp = pcbdoc.findcomponent(refdes)
comp.selected = true
if the U1 component exists it will be selected in the board. With cross-probing turned on, it will also be selected in the schematic.