Trying to create an Entry box that only allows hexadecimal values to be entered.

I’m trying covert a hex document data from a different file format and having the data start from a specific address that stated within the code. ive tried using a python script using intel hex but only seem to get text documents that add the address added onto each line. but once converted in notepad plus the address will be added to the dump instead of changing the address. does anyone know any solution to this, open to using different languages if need be.