I found this line in WinAmp.ini
dspplugin_name=
so I guess a simple AutoHotkey
IniWrite,path to the dsp,C:\Program Files\WinAmp\WinAmp.ini,Winamp,dspplugin_name
should work. But you probably have to reload WinAmp, so it's not ideal, unless there's some other way of forcing an ini reload.
Skrommel