This is still a good suggestion to point VirtualBox.
Indeed I am still using vmware because I started with their 1st VmWare Player that was (I believe so) the first free VM, before VirtualBox and not including buggy VirtualPC.
I was too lazy to switch up to now, but maybe it's time now. Especially if I can find a way to migrate easily my VM to VirtualBox.
I also had a look to TCL boot command settime but apprently this one is deprecated.
For now I have partially solved my problem using ntpclient in my bootsync.sh (I had to figure that ntpclient.tcz have to be one of the first tcz in my onboot.lst to work properly ...