I'm gonna give you the step by step, please don't be insulted if you already know or could figure out one or more of these steps.
In the editor, go to the alchemist archetype you created.
In the upper right is a button marked "Eval scripts". Click on that, and at the top there will be a bit of text "Click to add another eval script", which you should click on. The window will change to a header with "Phase", "Priority", and "Index" over a big grey box. In the dropdown to the right of Phase, choose "Final", and in the small box to the right of Priority enter "99999999" (but without the quotation marks, just the number). That is 8 Nines. Index is not important, you can leave that alone.
Now, in the big grey box paste the following script:
Code:
~ We must overwrite the Spellbook expression, since we need to make them use a different spell list. Since Alchemists create their allowed spells from the ones in their book, we don't need to do anything further than this.
linkage[varies].field[cSplBkExpr].text = "(sSchool.Metal | sSubschool.ssODclwk) & !Helper.Hide & !Helper.Obsolete & !Helper.Helper & !(component.EffectWord | component.MetaWord) & !Helper.WordSpell"
Now hit the OK button to close the Eval script window. In the upper left of the editor, hit the blue "Test Now" button while the archetype is selected.
Now create a new portfolio to test things out on. Add a level of alchemist, go to the alchemist tab, and click on the spellbook. Click the button to add a spell. You should see the normal variety of alchemist spells.
Back out and return to the Classes tab, and add your archetype. Then return to the alchemist tab, click on the spellbook again, and again add a spell. If you followed the steps above, you should see a different set of spells to select from. If you don't, then something went wrong, and double check your work. All else fails, give the forums another shout and we'll see what we can do.