What you want to do should actually be possible.

First of all, you'll want to download the Canon SDK (Software Development Kit) from http://www.usa.canon.com/cusa/consumer/standard_display/sdk_homepage.

Since you appear to be in Europe, your page is http://www.didp.canon-europa.com/ (found from the Canon USA page linked above).

It indicates the SDK is compatible with the 550D, although you'll have to submit a registration to download the SDK (Canon makes you promise not to do some things to their cameras that they feel will be detrimental to their business).

The (possibly) tricky part is the kit has been written in C. This means that you'll need a bit of developer skill to link your code (C, C++, ObjectiveC or other C-linkable language) to the Canon libraries. It's not insanely difficult, but if you've not written code before, you'll probably want to find a developer friend to help you get set up.

I have no idea if your turntable is accurate to 10ms per revolution, but setting your initial loop to 1820ms (1.82s) would allow you to determine how accurate the whole setup is, and allow you to tweak from there.

Once you have a simple initial app which, say clicks the shutter every 1810ms or 1830ms (this will give you the two decimal place control you are looking for), you may find that there is a lag preventing low latency (ie. you cannot precisely time the first shot), but the lag should be very consistent, giving you high accuracy in your relative timing (ie. the shot-to-shot time should be the proper interval).

I hope that is helpful!

-bRad