Hi,
as Luke mentioned there is no way to do a mass upload for talent pools either from backend nor form WD fronted.
If it is although necessary to perform a upload from my perspective there are three ways:
1) Create a ABAP program which stores data to the infotype.
2) Crate a Backend UI for the infotype 7420 and use LSMWto upload data from a excel file
3) Use a third party tool to execute the frontend several times to upload data ( maybe load runner )
best regards
Martin