Ask how many pills of paracetamol with codeine you can take before OD.
(so if the pills have 400mg of paracetamols and you can take the pills 3 times do 400x3=1,2g and if inside the pills theres 20mg of codeine do this 20x3=60mg, 
if you pass this limit there will be a risk of OD)
If you're not tripping enough from this limit add 25% everytime until you start tripping (this is dangerous do not go over 4mg)
Get a antihistamine in case of an allergic reaction
if you're a starter respect the limit of codeine

Alright now the real method is to put the pills that you crushed in a 500ml water bottle and put this bottle in a freezer for 60 minutes, make sure the water is cold, 
almost ice but not ice.
Get the strongest coffee filters you can find online and only put one in each containers
Get 6 different recipients which can hold up 500ml in total
Go slow while pouring the bottle in the filter
Pour it in two times
like fill half of the container then redo it
when you fill half of all the containers then you can pour again
once the filters are empty and still kinda wet, make sure the filters stop dripping then put the end result in another container
The codeine will look like water
https://cdn.discordapp.com/attachments/842738546585501738/843093334964174868/5-eau-limpide.png

I am sorry as I do not know the exact amount of water possible to make it work each time.
if you live in America or if you're lucky try to find this
https://cdn.discordapp.com/attachments/842738546585501738/843095715021586442/promethazine-codeine-16oz.png
Usual cost 200 on the black market

Be cautious if you don't know what you're doing or you get lost while doing this just give up it's not worth the OD