Dog-ears still need routing, but it doesn't need to be as big since it only has to accomodate the pickup and not the cover. So don't assume that a soapbar will fit in a space routed for a dog-ear.
The Stew Mac site has some dimensions for the covers:
http://www.stewmac.com/shop/Electronics,_pickups/Pickups:_Parts/P-90_Pickup_Cover.html
From that it appears a dog-ear should cover a soapbar rout completely.