I think the other way Richard is referencing is something like this:
-take your original .wav or .mp3 file and add the amount of time you want as silence to beginning of track and then save it as something easy to remember (or add another smaller track, whatever floats your boat). You can do this quite easily with audacity, if you are unsure just ask.
-Now start a new sequence using the saved music file from above and save the sequence. This is so HLS converts the .mp3/.wav to a proper .PCM
-Copy the new .PCM file to the folder that holds your sequence and overwrite it.
-Now launch HLS and open your sequence and you will see all your effects start as if nothing changed but when you play the music you will notice the new music will play with the added silence or whatever you decide to add to the audio.
-To fix the effects not lining up, all you have to do is use the "Skew entire sequence left/right Number of tics", select Right and put in the number of time tics you added.
Everything will line up and you can add effects to the extra space, all effects will be there....
Of course, backup your sequence folder for the song in question before you do this just to be safe.