Create a plane in 3dsmax and rename it with efx_01,link it to dummy(root_point)
and export the diesel with name(in that case)efx_ littlefall.diesel,in this root:
C:\Programmi\Ubisoft\Ghost Recon Advanced Warfighter 2\Data\objects\effects chose the script xml u have create,here an example:
<?xml version="1.0" encoding="iso-8859-1"?>
<dynamic_object xmlns:xi="x">
<diesel file="/data/objects/effects/efx_littlefall.diesel" orientation_object="root_point"/>
<object name="root_point" hidden="true"/>
<object name="efx_01" hidden="true"/>
<effect_surface name="water01" disable_culling="true" object="efx_01" effect="littlefall" spawn_rate="50" active="true" start_time="0"/>
</dynamic_object>
In that root :
C:\Programmi\Ubisoft\Ghost Recon Advanced Warfighter 2\Data\effects u must create a script named e_littlefall.xml contain this script
<effects>
<effect name="littlefall" test_plane_width="1000" test_plane_height="0" test_nr_instances="1" test_spawn_offset="0" test_spawn_rate_hz="40" test_unit="" test_effect_surface="" >
<particle_effect test_name="waterFog" num_particles="1" time="5" align="normal" normal_align="velocity" gravity="0 0 -62.9962" gravity_align="world" velocity="0 0 1737.72" >
<visualizer type="halo" >
<data image="smoke_plane04" blend="add" billboard_type="normal_locked" size="1 1" size_min="100 800" size_max="150 400" render_template="effect_geometry_fade_out_add" />
<assign_particle range="0 0" />
<opacity_controller >
<key t="0" v="0"/>
<key t="0.0500928" v="50"/>
<key t="0.986201" v="0"/>
</opacity_controller>
<size_controller >
<key t="0" v="0 0"/>
<key t="0.577236" v="1 1"/>
</size_controller>
<color_controller >
<key t="0.00817439" v="223 235 255"/>
</color_controller>
</visualizer>
</particle_effect>
</effect>
</effects>