Run WinUAE with the -disableharddrivesafetycheck option, load your Workbench configuration, go to the Hard Drives section and click on Add Harddrive. Choose your memory card. In AmigaOS run HDToolbox. Point it to uaehf.device instead of scsi.device, either by editing the tooltypes, by entering it as a shell argument or by using the askdevice tooltype if on OS3.5 or higher.
Bye,
Thomas