Couple of things worth considering - support for modern hardware on windows 98 is a bit of a pain. You'd be better off running this in a VM - I believe VMware has native drivers, but virtualbox does not. I ran this in virtualbox but chances are this should likely work on physical hardware as well.
There's a bit of software called scitech display doctor that acts as a sort of 'universal' driver that might work. It was shareware and the company is defunct - so a little googling may be needed to find more information. There seem to be copies hosted here with officially released freeware codes for it, though this is until 6.x. There's copies of a beta version of 7.0 floating around (which is essential on virtualbox - and may work if the older, freeware versions don't work) as well which might be of use. I'd give this a shot to see if it does what you want it to do.
This does rely on the video card working well in VESA mode, and your mileage may vary. I've broken an install getting this to work, and the best option is abandoned, beta quality software so I suggest backing up before you try this, and backing up often.