Hi,
I use a voodoo3 3000 AGP.
I had the same proble first time I installed MOS 1.4 from scrach.
To resolv the problem, I took my old MOS 1.3 installation and Upgraded it to 1.4. In this way, I think MOS1.4 keep screenmode settings.

So try to install an old MOS 1.3 and then Upgrade it.