I found this in the netscape.public.mozilla.os2 newsgroup:
You can use it with Mozilla Firebird.

Change the CMD file to do DLLRNAME on MozillaFirebird.exe instead of gfx_os2.dll

Mike Kaply
so I opened up install.cmd in E, then control-F'd to do the following 2 find/replaces.
Find: components\\gfx_os2.dll
Change To: MozillaFirebird.exe

Find: components\\gfx_os2.bak
Change To: MozillaFirebird.bak