All of our products have minimal weight, but are shipped in a cold pack. No matter how many items, the total shipping weight is 3 lbs. Where/how can I set this value so I can get the correct shipping cost from UPS?
How about set the parameter... $initialpackweight=3; ...but set the weight of each product to 0.01 You have to have a positive weight for products as otherwise they are not counted for shipping, but that way you can have a very large number before they would affect the weight.
I like Vince's suggestion, but really, that will return a shipping cost for 4lbs as ups will round up to the nearest pound. So I recommend this $initialpackweight=2.1; ...but set the weight of each product to 0.001
This way the customer could buy over 1000 items and still get a rate for 3lb returned.