Set custom dropping threshold for IncompleteCholesky?

IncompleteCholesky is said to be "Modified Incomplete Cholesky with dual threshold", but it does not support setDroptol() setFillfactor() as in IncompleteLUT.

Its source code comments that:

Dropping strategy : Keep only the p largest elements per column, where p is the number of elements in the column of the original matrix. Other strategies will be added

So, the number of nonzeros in L is the same as the input matrix A.

There are problems that favor stronger preconditioners, and more fill-in can be allowed. What's the recommended way to modify the IncompleteCholesky source code to support more flexible threshold? Thanks!