Rusty..
Theres a few guys out there who validated a UK CPL onto a FAA Foreign Based PPL which was used to "Park" a FAA Type Rating (p1 or SIC) on. As this Type had "US - TEST PASSED" on it it could get transferred directly onto a US ATP later on in a persons career.
As the license is already a validation of a foreign license IOM wont validate it unfortunately. In the main they tend to be SIC guys who try to do this and get knocked back - could it be this you're thinking of?