Use the object-data-array syntax:

{"%_BUF1"}[index] – for the primary buffer and
{"%_BUF2"}[index] – for the secondary buffer.

For examle:

     DATA = {"%_BUF1"}[15]

Gets the 15th integer from the primary buffer.  See the Kmax manual for the buffer storage format.7.1 How do I perform a guassian fit on my data from Command Sequence Language?
Use the PEAK_FIT CSL Extension to perform a guassian fit on your data. This CSL Extension is part of the standard Kmax distribution.