Im not sure specifically how to direct you, some thoughts for consideration, maybe something will be helpful.
1) On ebay I also see system utility disks as well as operating system disks. If you have that disk for your system, maybe it's bootable and you could get started that way. (also, I dont know if "dell" win98 is different than a microsoft 98 cd, if you have a microsoft win98 cd you could try booting the system with that.)
2) If the harddrive removes easily, you could consider getting an adaptor kit and putting it in a desktop as a slave, booting the desktop with a win98 bootdisk and then copying the win98 directory from the win98 cd, put the drive back in the laptop and go from there. (I have done this general concept with win95.)
3) I was cleaning up my computer the other day and I found this site reference - I've not waded through it and I suspect it takes at least some files on the system, but I pass it along for whatever it's worth.
4) If the harddrive does not remove easily you could consider making a boot cd with the win98 boot disk info
(
if you dont have one). I've never done this so I cant comment on how well/poorly the attached comments/instructions work.
If you also put the win98 directory on the boot cd, you could then copy it to the harddrive after you formatted it.
The best optimizer is between your ears.
M. Abrash