It should be possible to just copy/paste it. Stuff in the JS tab is run in exactly the same way as <script type='text/discourse-plugin>. If it’s not working, can you share the code?
With some crazy modern CSS, it’s possible:
.d-editor-container:has(.category-input .select-kit-header[data-name="Support"]) .tags-input {
display: none !important;
}
^^ this hides the tag input for the “Support” category on Meta.
You can swap the [data-name="Support"] for :not(data-name="Support") to reverse the logic.