Change trails settings while its active?

How can i change the settings of util.SpriteTrail() without loosing the existing trail?
Or is there maybe another way to create trails, one which would allow settings to be changed while active?

Store the returned env_spritetrail entity and change its keyvalues with SetKeyValue()

Completely forgot about env_spritetrail. thanks.

util.SpriteTrail returns an env_spritetrail.

[lua]
local trail = util.SpriteTrail( blah )

print( trail:GetClass() )

[/lua]