invoking ff from non-photoshop host

[Dave Dyer <ddyer@bigfoot.com>]

 I'm writing code to invoke ff filters from a non-photoshop host,
and would like to be able to manipulate the parameters from my own
UI.  It appears that there is a block of 10 longs which contain the
slider data, at an offset of 25(longs) form the parameter table.

 It seems extremely likely that these magic numbers are specific
to a particular version of ff. What is the recommended procedure,
if any, for dealing with this?