I photographed the ISS transiting the Sun
from Shannon Airport about a mile West of the centerline for this due to thick fog!
Luckily the weather stayed clear there just long enough to catch the pass.
Not particurally ideal conditions added to the fact that the ISS is about as high as it gets in orbit right now (the distance from my point was 1020.5km!) and the Sun's altitude was only 16 degrees high.
I used a Canon 350D with an f6.3 focal reducer through a Meade ETX-125 OTA manually guided on a Manfrotto photographic mount.
I started the photo run 2 seconds before the predicted transit time and ran 2 seconds after
at 1/1200 sec shutter speed, ISO800 on multi shot mode.
After the pass I scrolled through the shots and found I'd captured 3 seperate images of the ISS moving across the suns disk during the 1.23 second transit.