OS Commerce disable a shipping module based on total amount

I want to disable a single shipping module ([login to view URL] for uninsured shipment) if the total order amount is higher than 50 Euro. All other shipping modules should be kept enabled. I currently use 4 currencies in the shop (EUR, USD, GBP, CHF). The fastest way would be to hard code something into /includes/modules/order_total/[login to view URL] to skip the module [login to view URL] if the $total_amount >= 50 Euro (or that value in USD, GBP or CHF). The most elegant way would be to edit [login to view URL] to allow for entering an EUR amount in its admin section modules/shipping. If later on this amount is exceeded by $total_amount the module will be disabled, same as if I clicked "enable = false". Please post with your quote wether you refer to the "quick & dirty" ot_shipping method, you'd edit [login to view URL] or if you'd use a totally different (possibly ingenious) apporach.