Yes polishing aluminum is a very messy job, the black aluminum oxide goes everywhere. Cleaning up the residue really depends on 2 things, the carrier or based used in the polishing compound you used and the surface you are trying to get it off of.
First if the surface it is on is gel coat it is much more resistant to stronger cleaners and solvents than paint
, On gel coat you can use very aggressive solvents like acetone and even lacquer thinner whereas on paint you are limited to the less aggressive solvents like Varsol and paint prep. Be careful that any cleaning agent you use will not damage the finished surface. The problem with older gel coat it the staining will get right into the porous surface and is very difficult to remove, in this case just keep working on it to "flood" the stain out
If you used a polishing bar it is wax based and I actually found soapy water was one of the best cleaners, also try Simple Green or Spray Nine. Often these water based cleaners work very well, if they don't then do try a solvent that will not damage the finished surface.
As for another way to polish your aluminum, first I would recommend removing any aluminum, polish it then reinstall, if this is not possible then you definitely want to thoroughly mask off the area to protect the finish from both over-spray as well as damage from the polishing wheels.
To truly polish aluminum you have to use a compound based product and take the time to actually smooth out the surface of the aluminum to a perfect mirror surface, with polishing wheels, time and effort, there is no easy or magic shortcut. All the magic creams, and "wipe on Wipe off" products do is chemically remove the oxides which makes the aluminum look better but it will never achieve the level of shine produced when machine polished and the oxides will return in a very short time. Aluminum which is correctly polished will actually resist oxides because of the reduced surface area and keeping it shiny takes very little time