[Wine] How does Wine simulates Windows presence?

[fafner]

Here is a rather technical (and maybe strange) question: how does Wine simulates Windows presence at the low level?
I know that operating systems usually make themselves present using interrupts (for i386 at least), for example interrupt 0x21 for DOS and 0x80 for Linux. I suppose there is another interrupt used by Windows too. What I am wondering is how Wine makes it available to the Windows executable loaded in memory. I have read a big amount of source code from Wine (although not even 1% I'm sure), but so far no clue about where this small initialization code is hidden. Could someone point me to where it is, or even better, to a documentation?

Thanks in advance :-)

PS: In case you wonder why this would interest me, the reason is I just want to mess with this mecanism for fun :-P