The only way this can work is when you have 2 primary partitions on HD 1: you will need partitioning software (f.i. Partition Manager from Powerquest,....). On these 2 partitions you will have one after the other both OS, i.e. Win98 and ME. You cannot boot from a second HD, installed as a slave to the first HD.
You could however "move" the ME OS after having created the 2nd primary partition on the first HD and use the second HD for logical (i.e. data, backup,...) partitions.
I think that you can also find some freeware partition managers, but you will definitely need to start reading about partitioning, booting from different OS, installing a second HD in your PC, etc.... before you engage in anything of this kind !
It is worthwile however...
Anyone another advice to help Carlsberg?