Association algorithm itemsets

What is the algorithm that generates the itemsets in the Association model? I'm looking to possibly use this part of the Association algorithm (i.e. the grouping into itemsets) in a separate plug-in algorithm.

The algorithm is based on the 'a priori' technique. Basically, 1-itemsets are filtered based on certain thresholds, then the algorithm moves to computing 2-itemsets and so on. Brief details on how Microsoft Association Rules work: http://msdn2.microsoft.com/en-us/library/ms174916.aspx

Hope this helps