is OP a mod? how did he know what his postid would be before he submitted it? spraying [sequential] submissions all at once?
[edit]
[edit]
(edit: nope, I was 3 off, you get the point though, apparently a lot of people are commenting at the moment, ha)
The easiest way to do it would be to pick an ID in the future (say 20 ahead of the latest one) then type the title and link out, then just keep refreshing the page for your selected ID minus one (for example, if your chosen ID is 3743040 refresh news.ycombinator.com/item?id=3743039) until you get a result then hit submit, if you're not too slow you'll get the ID 3743040.