To do this, first open up Calculator. Find out how many days it is between now, and the BIOS date you want. For example if you wanted a Whistler build, a date of 1/1/2001 would be okay. Using a calendar or by using this site you can get the number of days. Between today and 1/1/2001, it's 2386 days.
Now, multiply the number of days by 86400000 (which is 24*60*60*1000) to get the number of millseconds between now and the target date.
Fire up Command Prompt, and CD to the folder containing VirtualBox (most likely c:\program files\innotek virtualbox). Now type:
Code: Select all
VBoxManage modifyvm <name> -biossystemtimeoffset -<milliseconds>
Example:
Code: Select all
VBoxManage modifyvm "Windows Whistler 2419" -biossystemtimeoffset -206150400000
I know, it should be 2419 in the screenie but I installed 2296 instead, and I used a different time offset.