It seems to work if you first implement the OnChange javascript. Then export the solution and fix the lookup view. But I guess without any guarantees...
I used this script, works excellent: crmuk.wordpress.com/.../crm-2011-set-default-unit-when-selecting-a-product
And then the "parent" view fix from: crmandsharepoint.blogspot.se/.../view-products-in-parent-price-list-is.html