There's a generic binary BIL / HDR format out there for Floating point raster elevation data where the header does not conform to any of the BIL headers interpreted by ERDAS IMAGINE's direct reads. However it can be imported using the Generic Binary importer so long as you specify the number of rows / columns (usually 3001 x 3001), etc.
This Spatial Model shows how to parse the header to produce inputs to the Generic Binary importer and to the ImageCommand executables, both run via Command Line operators. This way the import process can be easily Batched if there are a large number of such BIL / HDR DSMs requiring conversion.
….but most of those can be easily changed (or variabalized) if you want. The ImageCommand executable could also be used to apply a vertical datum and other information normally associated with a raster elevation file.