If it is not obvious that the installer is going to put grub on the first drive, you can always put it on a floppy.
Also, you should be able to install grub from the install CD. Boot from the CD and--as soon as it is up a running, type ctrl-alt-F1. This should get you to a command line.
Here are the steps to install grub from any Linux command line:
I'm assuming IDE/PATA, and Fedora all on one partition (/)
grub starts the grub shell
root (hd1,0) Tells grub that "home base" is on the first partition of the 2nd drive
If you have FC6 setup with a separate partition for /boot, then the "root" statement above needs to point to that partition.
Now you have to edit the /boot/grub/menu.lst file to make sure it is setup correctly.