From discussion in Shao's topic GRUB4DOS RAM Disk Recognized by RAMDISK.SYS, I try making a Windows driver to read GRUB4DOS' drive map table and use GRUB4DOS RAM drives in Windows. This driver is the result. It emulates SCSI adapter and disk. It can use RAM disk loaded by GRUB4DOS in Windows.
Shao's driver WinVBlock can also use GRUB4DOS's RAM drives. You can visit his thread for more detail.