I got MHVTL to work on Windows via iSCSI .
I used Generic SCSI Target Subsystem for Linux from http://scst.sourceforge.net/
See this How to install scst on Gentoo Linux http://iscsi-scst.sourceforge.net/SCST_Gentoo_HOWTO.txt
I am using mhvtl release 0.18-1 http://sites.google.com/site/linuxvtl2/mhvtl-2009-12-15.tgz?attredirects=0
For an ISCSI initiator, I used Microsoft iSCSI Software Initiator Version 2.08 on Windows 2003.
I was able to connect to the targets and see the changer and drives. I had to install some drivers for the tape drives afterward.
Then I used networker to check the tape library and tape drives.
>>>>>>It all worked just fine.