how to specify my conditions in hMETIS

I want to use hMETIS for partition, but I want to terminate the partition when my
condition is met. For example, the partiton is performed recursively until the number
of registers in each set is less than threshold Xth. Since hmetis is invoked by providing 9 or 10 command line arguments, one of them is the Nparts-the desired partition number. But I don't know how to use hMETIS for my use described above.
And if I want to specify the cost function and balance function, other than the functions in hMETIS, how can I use it ?
Thanks a lot.

RE: The short answer is that you

The short answer is that you cannot do something like that in hMetis.
Now, the long answer is as follows:
The first part, regarding the less than a threshold, you can achieve it by essentially asking hMetis to over partition the design and then write a small program to combine the small partitions that are well-connected until the threshold is violated. The second part, i.e., cost and balance function cannot be done (I presume you are looking for something like ratio/normalized cut).