Kreem is a soft, flexible fuel-proof coating, impervious to water and air with good adhesion .. this is why it can cover rust and not allow that rust to grow or flake off.
Although it can and often does plug small pinholes, it's not meant to plug holes..
that said, unless you can get at the hole(s) and then use something like an epoxy, one or more Kreem coatings may be the only practical solution... this assumes the holes are tiny. It may not plug larger holes.
Since it's vital to keep oil and gas separate, thorough testing and examination after the attempted repair might be wise..
oil does run very slow through the pump.. maybe an ounce per 25 miles of riding.. that translates to around one milliter (one cc) of oil per mile.