OK, I have to revive this thread for the sake of clearness. I hope that at least the persons who posted here can help me out.
The thing is that I can't make my soundscapes to work on my workshop after I packed them into the BSP. I tried packing only the 2 relevant files ('game_sound_manifest.txt' + 'soundscapes_[my_map_name].txt') under my portal2_dlc2/scripts folder first... no luck. I tried doing like Tmast98, packing portal2_dlc1/scripts + portal2/scripts to no avail. I even tried packing these 2 files from the 3 locations: portal2, portal2_dlc11 and portal2_dlc2... to no avail either.
HOWEVER,
I'm curious about how the sound system works, how pakrat exactly works in the inside, and what order of packing Tmast98 did exactly to achieve it. I mean that since you can only pack whatever files at a time located into the SAME folder, and due to pakrat will ask you to fix up the paths EACH time for EACH folder, the order here is CRUCIAL.
I mean that if for example I pakrat first my files under portal2_dlc2/scripts and say pakrat to fix up the paths to my files; then I pakrat my files under my portal2/scripts folder and say pakrat to fix up the paths again, wouldn't it only save the last information, being the files under portal2/scripts?
What if I first pakrat the files I've got into portal2/scripts AND THEN the ones into portal2_dl2/scripts? wouldn't the saved information be my files under portal2_dc2/scripts this time? I DO think so. Therefore the order is important with regards to this workaround Tmast98 posted... and pakrat will fix up the paths for the SAME files once, then again... and so on... for all the folders you want to pakrat your soundscapes from.
I still have to test properly HMW's discovery (sv_soundemitter_flush console command), but anyway, I'd really love to clarify all this mess regarding packing soundscapes from different folders, please H E L P 
Oh, I almost forgot to mention: since I've got pakrat set up to find any "soundscapes_[map_name].txt" (in File > Preferences), it DOES find my soundscapes file (it detects the copy I've got into portal2/scripts only) and automatically pakrat it, however it places the file in the /Root folder instead of inside a /scripts folder (and I suppose it doesn't need to since it fixes up the paths and the file could potentially be anywhere...); and it doesn't find/pack the "game_sounds_manifest.txt" file, but that is already knowm. What I'm asking to myself now is: should I pack again my "soundscapes_[map_name].txt" even seeing it is already inside, but from the dlc2 (or dlc1) folder this time... or just the "game_sounds_manifest.txt"? >.<