What is the best database engine independent way to load a huge amount of data.
While I'm using SQL Server I use SqlBulkCopy but want to untie from SQL Server
There is no database engine independent way of doing this. Each DB server has its own way (e.g. bcp for Sybase).
There may be some 3rd party product which can do the work for you but it will merely be a wrapper around server-specific methods underneath (If that's what you're looking for, you may want to clarify your question).
NOTE: doing a bunch of INSERTs as Mark suggested is definitely not the same, since INSERTs are MUCH slower than native bulk inserts due to being logged (unlike bcp).