I don't think what you're asking for is feasible, and you (or your manager) need to rethink your requirements (as well as doing some independent research).
This is a lot more work than I think you think it is.
The page that you're working with is
quoteitm/multilineitem.jsp. It's a standard UI that Salesforce provides, but doesn't allow you to tinker around with too much.
There is this help article which outlines how to add a field to the multilineitem.jsp page for Opportunity Line Items. The process is identical for adding fields to the same page for Quote Line Items.
- From the object management settings for opportunity products, go to Page Layouts.
- Next to the name of an opportunity product page layout, click Edit.
- Click Edit Multi-Line Layout.
Move fields between Available Fields and Selected Fields.
- To customize which fields display in the layout, select one or more fields in Available Fields and click Add or Remove.
- To sort fields in the layout, select one or more fields in Selected Fields and click Up or Down.
- To select multiple fields individually, use CTRL+click.
- To select multiple fields as a group, use SHIFT+click.
Click Save to apply your changes.
That can get your picklist onto the page, but I believe that making your picklist dependent on product name is out of reach. If you have a controlling field for a picklist, it must either be a checkbox field, or another picklist field.
For that, you'd need to make a custom controller or controller extension and manually create & maintain the dependency logic (which is well beyond the scope of your question). This also means that you'd need to override multilineitem.jsp, which is another nightmare altogether.