There's a Tack Conversion Kit for Hivewire Horse made by Lyrra Madril that convert Tacks for Millennium Horse convert to fit Hivewire Horse, Unfortunately hivewire3d since closed down and haven't put it in Renderosity. Maybe someday Lyrra put and update it in Renderosity (like Daz Horse 3 Tacks convert to Hivewire Horse only DS)

https://community.hivewire3d.com/threads/lyrras-products-at-hivewire.1593/