Can any explain how the alternate-categories technical works? Where is it store? How to backup it ?

Is there a import module for it ? Example i have the following ascii file:
field: id = 1 category1=0 (0 is not true) category2=-1 (-1 is true:)) category 3=0 category4=-1

example data ascii file is:
1|0|-1|0|-1
2|etc.

Is it possible to choose alternate categories when you choose add record ? Now it can only be selected/added when you choose modify links - alternate