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Welcome Chris!
I'm certainly no expert - but I think your challenge is going to be tracking, unless you're using a star tracker or equatorial mount. At the longer focal lengths you'll be seeing trailing stars after a couple of seconds without one. Use the image review and zoom all the way in to see this. Maybe start at the 55 end and see how far you can push the exposure time.
I find the ISO sweet spot on the 1100D to be about 1600 for long exposures (a couple of minutes), although the only thing you can really do is experiment...without tracking you're going to need to pump up the ISO, but you should be OK as the short exposures should keep the noise down.
The other thing is take LOTS of pictures, one after the other. 20-30? More is more! Then stick the lens cap on. Take a similar set. With these you can use a program called Deep Sky Stacker to add all the frames together and see what you get.
Good luck and keep us posted!
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