Hi Sieg,
Scripting would be one option, but setting 52 fields using script would be difficult. Instead you could use this approach.
1. Group Jan 1st, Jan 8th, Jan 15th, .. +7 days,... in group 1. (As these days will be having same day in all years)
2. Group Jan 2nd, Jan 9th, Jan 16th.... in group 2. like wise make 7 groups.
3. In a group, make sure all fields have same names.
4. Now on a subform, write this script in javascript.
var fields = xfa.layout.pageContent(xfa.layout.page(this)-1, "field", 0);
for (var i=0; i <= fields.length-1; i++) {
if (fields.item(i).name == "FIELDNAME") {
fields.item(i).fillColor = '<Fill your color combination>';
}
}
--
Rakesh