Ah, OK. Well, that should work just fine too. You'll have to take care of the boot priority thing still, though.

Assuming the disk is blank, open up HDConfig from the Tools drawer on your MorphOS partition. Find the disk in there, right click on the disk icon on the left and make sure 'RDB' is selected. Then click on the empty space to the right of the disk icon. Create one partition. Click on the newly created partition.

First you want to make sure that the partition is no more than 2GB big. To be on the safe side, in the field labelled 'Size in MByte', choose a value less than 2000. Under 'Status:', choose 'boot with priority' and set the priority to -1. Filesystem should be set to 'FFS Intl'. Finally, if you want your disk to work a lot faster at the expense of a little bit of space waste per file, choose a block size of 4096. Click OK and click on the save button that appears under the disk icon in the previous window.

You should now be ready to format the partition through Ambient and copy files onto it.