FIFO(first in first out) implementation In VB.

Hi friends,
In my project i am using 6 forms. Each form has a check box.Now the condition is, at any point of time not more than one check box should be checked(value = 1). If at any point of time, if a check box in one form is checked then the other forms should wait for that checkbox to get unchecked(value = 0).If there is a clash between 2 or more forms to check its checkbox then the form which waited for long time should get oppurtunity to check its checkbox.Other forms should wait until this checkbox gets unchecked. Thus the forms should get oppurtunity in first in first out order to check their their boxes depending on time they waited. I am not getting how to implement this FIFO in VB. Can anybody help me in providing an idea to proceed or a peice of code to implemeny FIFO. I am using VB6. Thanks in Advance.The time to Check the checkbox is indicated through Auromatically controlled condition.