The frame will need to have the Mounts on it , and the fork to have another set.
they would both be on the left side ..

there are a few different IGH with disc mounts
Sturmey's 8 speed you need a pretty small chain ring up front ,
because other than Low the gears are all overdrive .
so with bigger wheels the ratios get huge and useless pretty soon.

A 5 speed OTOH has 2 reduction gears and 2 overdrive gears.

for a frame without the disc mounts , consider Sturmey's Drum Brake Hubs.