The Readme file of IE 6 has this information, or You have it at the link
bellow yes IE 6 on Win NT is possible

Internet Explorer 6 Public Preview Readme.txt File

http://support.microsoft.com/default.aspx?scid=kb;en-us;292243

Kutts (Kuttappa K A)

This posting is provided ?AS IS? with no warranties, and confers no rights.

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==Content-Class: urn:content-classes:message
==From: "Arthur" <anonymous@discussions.microsoft.com>
==Sender: "Arthur" <anonymous@discussions.microsoft.com>
==Subject: IE6 and NT
==Date: Mon, 7 Jun 2004 10:24:30 -0700
==Lines: 6
==Message-ID: <1936e01c44cb4$4ab7f2d0$a401280a@phx.gbl>
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==I am running Windows NT ver 4.0 SP 6 on my workstation
==with IE 5.5. Can I upgrade to IE 6.X?
==
==Thanks
==
==Arthur
==