Limit Free Shipping Coupon to low cost option

[Zean]

Discount Coupons
Free Shipping

How do we create a Discount Coupon for Free Shipping that applies to only certain shipping methods? For example, coupon name: Free Slow Boat Shipping.

I offer many shipping methods and options. For example, Option one (1) is via "slow boat" and costs me a few dollars. Option two (2) is next day and costs me $50 to $100 or more. I can't afford to give next day shipping for free.

Therefore, I want to create a "Discount Coupon" for "Free Shipping" but want it to apply to the "slow boat" shipping method only. How can that be done? Thanks.

Zen Cart 1.3.8a

[Ajeh]

You might look at this thread on how one method was used to control the shipping method when the Discount Coupon was for Free Shipping ...
http://www.zen-cart.com/forum/showthread.php?t=75489