If you have the stockists module activated you can create a stockist from a customer flag in Attache. This will add them to the web stockists lookup on your site. So let's take a look:
Site Configuration for Stockists Import
1. Login to the admin area
2. Select Configuration > Attache
3. Select the appropriate Attache field you'd like to use as your stockist flag
4. Click Save
Flagging a customer as a stockist in Attache
1. Login to Attache
2. Go to Masterfiles > Customers > Maintain and select a customer you would like to turn into a stockist on the site.
3. Ensure you have the appropriate contact information filled out
4. Page down twice and ensure there is an email address in the Email Address field
5. Page down and add a Y in the field you nominated in the site admin, in this case Yes/No 2
6. Save the details and run a sync in the web admin area. The stockists will update to the site.