Ask YC: Bitmap index on mysql?

I have a huge database of 10 million+ rows that I need to select from. I can fit the selection criteria and format the data into about 40 columns each with a small number of distinct values. In this way, complex selection queries would work great with a bitmap index. The only problem is that mysql doesn't seem to support them. Has anyone else had this problem? If so, what have you done? Do I need to get a new DBMS - or is there another way?