Hmm... Assuming that the drive is hooked up properly (which it probably is, if it didn't smoke and blow up when powered up) you'll still need to do a couple things to it before it'll show in Workbench.
1) boot into workbench off the install floppy.
2) run HDToolBox from the install floppy (not an install language, but there should be an icon named HDToolBox)
3) Locate the drive in the HDToolBox app, and go in and partition drive to your liking.
3a) go into Advanced... for each partition and set "Max Transfer" to "0x1FFFF" (Don't ask - just do - trust me!)
3b) Close the advanced area and then write the changes to the drive.
4) Exit HDToolBox and reboot as required, but leave in the install diskette
5) Once you are back in workbench, you should now see something like dh0:

? That's your first partition (you'll have dh1:

? and whatever else for the rest of the partitions if you made multiple ones) Format the Partition(s) you created. You can do this by simply picking the icon and choosing "Icons > Format disk" from the pulldown menu, or running sys:System/Format
6) NOW run the installer language of your choice. You should have much better luck. :-)
- If at step 2 you don't see any HD's in the HDToolBox app, close the app, and click on it, and choose "Icons > Information..." from the pulldown menu. Make sure your device is set to "scsi.device". Another strange quirk of the 1200. Even though it's an IDE drive, you MUST use scsi.device.
Let us know how things go!