Thanks for your help, but i dont think that this could help me.
The values that i have are calculated and are different for every bug.
So in example:
#454 > Value1
#455 > Value2
#456 > Value3
The thing is that Value 1, 2 and 3 are calculated in an external system, and this is the information that i want to show in mantis by filling the value of the custom field with them.
Hope that is more clear now, and thanks again for the link.