You can use BSP Factory to convert Half-Life BSP files, which you can create with Quark or Qoole, into Blitz3D .b3d files. BSP Factory has been temporarily removed from sale, because the company who published it, Binary People, has closed. I will start selling it by myself (I am the developer of BSP Factory) using ShareIt. Anyway, if you are interested in purchasing it (it costs $15) and don't want to wait, contact me.