If not you're out of luck with InstantKB 1.3. I assume InstantKB 2.0 will have the language xml files that InstantForum 4.x has so you should be able to change this in the next version.
I found the place you need to change it on line 597 in Controls.vb (in the InstantKB.NET Source Files folder).
sbForRender.Append(""" class=""" & m_linkClass & """>Home</a> ")
http://www.the-pork.net ... highly customized version of InstantForum.
Dear reborn,
Open a ticket in our ticketing system (http://my.instantasp.co.uk) so that I can change this for you and send to you the dll file.