interrupt 13h and 31h

I am porting DOS application to the Windows 16-bit (Win3.1, 95)
MS Visual C++ 1.51, large memory model
Programs reads floppy disks that are not in DOS format, so interrupt vector 0x1e should be redirected to point to the user-defined floppy description table.

First I declared user-defined table strucure:
struct
{
...
}TABLE;

Then I declared:
TABLE *my_table;

Then I used in31h with AX=0x204 to get selector and offset of the default floppy table. I don't know how to get poinetr from selector and offset.

Then I was going to use int31h, AX = 0x205 to set vector to point to my_table. I need selector and offest, but I have pointer. How to translate poinetr to the selector and offset.