How to get the "build date"

I want to set a register value to the build date and time of the install. Not the global variable %CURDATETIME% as this gives me a new date and time of when the installed was executed. I want the date (and time) when I press the “Build Now” button on the Paquet Builder project.

Just to make thing more clear: Lets say I build a new install on 2015/03/05 at 12:00. I thus want this date and time to be added to the register even if I run the install 10 days from now.
Possible?

I found a solution to my own problem. I use the macros _DATE_ and _TIME_ in a c function. Works perfectly!

Thank you for the advice. Looks like support for custom C code in Paquet Builder is a great addition for specific cases like yours.