Hi,
In order to interface to ISA, you must first differentiate that you wanna data transfers from CPU or DMA? This is done using AEN signal. Then you have to decode an address range (or a single address) that you 8052 will respond to. Also you have to decide that you want to place your h/w in I/O map or memory map. This selection is performed using IOWR, IORD, MEMWR, MEMRD signals.

However if you can contact me on email, or ICQ, i can teach you more. I have done lot of projects on ISA slot.

Best of Luck