Adjustments for OpenCart custom mod.

i need some changes made to an earlier modification for opencart 1.5.1.1. It is a module for shipping adress per item. In this is an option to select a date (for pickup). What needs to be made is that after 16:00 server time, no current date, can not be selected anymore. This time needs to be adjustable from admin of Opencart. Also in shipping address per item is size per item. here is size in centimeters filled in. For this 3 fields, (length, weidth, height), a formula needs to be developed, that displays an error when the values are higher as the formula allowes. This needs to be done as following: 1 X length 2 X weidth 2 X height entered in cm. the outcome of this needs to trigger an error message, or not. (not allowed to order, or allowed to order). For example: Length: 10 cm Weidth: 20 cm height: 32 cm Formula needs to calculate in background: length X 1 = 10 X 1 = 10 Weidth X 2 = 20 X 2 = 40 height X 2 = 32 X 2 = 64 total = 64+40+10=114. This outcome of total (114), is the number that needs to be matched to an entry that can be made from admin of opencart. If i enter in background of admin 300, all outcomes with a total that is less than 300, like 114 of the formula above must be allowed to order, just like it is now. (no error messages, nothing). If total of formula above is above the amount entered in admin, (300), a custom error message needs to be displayed, and order must be not possible.