check box via win32 api

[paperson1984]

I am working in a modeling program with limited VBA functionality, and am trying to check a check box in a window.

Here is the info I do have:
A) I can easily get the handle for the window that contains the check box with the program's VBA functions.

B) I have the class from Spy++ (it is a ThunderRT6checkBox). The caption is constant.

C) For this implementation, I can assume the window containing the box exists, has focus already etc.

Is there a way using the win32 api to get this check box to check? I am thinking something along the lines of a SendMessage (tho I know nothing about this, I've seen it used to accomplish similar tasks before), or any other ideas.

Thanks!

PAP