I thought I could just note another solution to this problem - install the 1.4.2 JRE along with other JRE:s, and then update the NCF startup scripts to force the framework to use a specific JRE, not the "system default":
[NCF base directory]\bin\setLitePath.cmd defines a 'javaPath', i.e.
(or whatever JRE you would like to use)
set javaPath="\Program Files\Java\j2re1.4.2_15"
bin\startNCF.cmd and bin\startNCFFull.cmd prepends the invocations of javaw with this path, i.e. in startNCF.cmd:
and similiar in startNCFFull
%javaPath%\bin\javaw -cp %liteCP%;%adminCP%;%externalCP% com.nokia.phone.tool.ncf.core.application.MainApplication Lite