First of all if the boot sector is bad on your HD you will not be able to use it as master but can use it as slave. If yoou want to get your system up so that you can get to the BIOS then make a boot disk. Go to www.bootdisk.com
and I believe the first on is for Win98. Of course you have to do it on another machine since yours is trashed for the moment. Also with some older motherboards you can boot from a video card although I have only recently read of that and dont deal with older computers myself. There is a discussion on that over at www.techspot.com
I believe it is in the CPU MOtherboard forum or the Windows OS forum, I just read it yesterday.
I am assuming also that F10 is the correct key to enter the BIOS
and if that is the case you may have trashed youor BIOS since the keyboard is the first device selected on a boot so if your BIOS is really fried perhaps it cant even initiate your keyboard. You may need a new BIOS if this is the case go to www.badflash.com
they are cheap and helpful.