WAV-PRG is a program able to The latest version of WAV-PRG and Audiotap can be downloaded at the Sourceforge page, in the Files section

Transfers between PC and tape are done by means of a simple audio tape player/recorder (a Commodore 64 datassette is not required), connected to the PC's sound card via an audio cable.

Creating emulator files from Commodore 64 tapes
Creating Commodore 64 tapes from emulator files