They are not usually hot swappable. In which case you will need to do it in two stages.
1. Use FDD (A:) and format Hard Drive (C:) - Turn off.
2. Connect CDROM (probably D:) and turn on. Enter BIOS to select boot from CDROM. Save and exit. When laptop boots from CDROM it should take you straight into a menu from where you can install.
Don't forget to reset BIOS to boot from Hard DIsk once 98 is installed enough to boot from C: