addlocalmodifier("range", 0.05, 2, "alpha", "replace", 0.99, 0); would reduce the alpha of the particle from 1 to 0 in the given timeframe of .05 to 2 seconds of it's lifetime.
Your question about addemitmodifier seems a bit vague - what it would do is change the angle at which particles are launched, but not modify it when it's in flight. addemitmodifier only effects what happens when a particle is initially fired, after it is in flight, global/local modifiers control what the particles do from there.
the parameters for each of the functions are as follows
addlocalmodifier(type, rangemin, rangemax, variable, variable modification, valuemin, valuemax)
Types - once, impulse, range - modifies the particle one time, periodically or only in the given time range
rangemin - seconds, minimum delay until first modification or start of modification range (if modifier is "range")
rangemax - seconds, maximum delay until first modification or end of modification range (if modifier is "range")
variable - x,y,z,movex,movey,movez,angle,zangle,speed,rotatio n,spin,stretchx,stretchy,red,green,blue,alpha or zoom
variable modification type - replace,add or multiply (if modifier type is "range" then only "replace" and "add" are valid)
valuemin - range start of the random value or first value to set/add (if modifier is "range")
valuemax - range end of the random value or last value to set/add (if modifier is "range")
from
http://wiki.graal.net/index.php/Part...icle_modifiers