How does one initiate a bull rush?

[Neowulf]

I'm having difficulty understanding how one initiates a bull rush

according to the rules

You can make a bull rush as a standard action (an attack) or as part of a charge.
so it would more or less roll like an attack, right?

then it says this under initiating it

First, you move into the defender’s space.
where it sounds more like a breath weapon, where there's no real attack roll to hit, but it just kinda happens by virtue of taking up the space

so, what exactly are the rules for this?

[Draconi Redfir]

So, granted this is pathfinder knowledge, i have no idea how you do it in 3.5, but pathfinder is better anyways.

in Pathfinder all you need to do is roll your CMB ( BAB+Strength Modifier, + size modifier, +other bonuses) to try and defeat his CMD (which is not rolled for) (BAB + Str, +Dex +Size +others +10). If you defeat the CMD, you push the enemy backwords one square, if you defeat the enemy by a lot (say he has CMD 10 and you rolled CMB 20) then you push him back further another square per 5 points beaten. (so beating a CMD 10 with a CMB 20 would push them back 2 spaces). And I’m pretty sure unless you have certain feats or class abilities, you need to get a running start to this thing, so you essentually need to make a charge attack without gaining any charge bonuses.

I used to have a character that would do a lot of bull rush attacks, and from what i recall this is how we did it.

[ExLibrisMortis]

0) Declare you're Bull Rushing the defender.
1) You move into the defender's space. This provokes, though AoOs against you have a 25% chance to strike the defender (except AoOs by the defender, but I hope you have Improved Bull Rush to prevent those). Given that it appears to be regular movement, it can't be combined with a 5' step on the same turn.
2) Make opposed strength checks.
3a) If you win, your opponent moves 5' back, plus 5' for every 5 points by which you beat the check. You keep moving with your opponent as you push them. Both you and the defender provoke by this movement, but not from eachother. As on step 1, AoOs against you have a 25% chance to strike the defender. The defender also provokes, and any AoOs against them have a 25% chance to strike you, instead.
3b) If you lose, you move back. I think this is not supposed to provoke, but it doesn't say, so it defaults to general movement, which does provoke.

[Necroticplague]

I'm having difficulty understanding how one initiates a bull rush

according to the rules

so it would more or less roll like an attack, right?

then it says this under initiating it

where it sounds more like a breath weapon, where there's no real attack roll to hit, but it just kinda happens by virtue of taking up the space

so, what exactly are the rules for this?

There is no attack roll. Success vs. failure is determined by the opposed STR check mentioned later in that section. The loser is shoved out of the square (back to the original if the one who initiated lost, in a direction away from the initiator's square of the defender lost).

The process is like this:

1.Attack declares bull rush, spend standard action.
2.Attacker moves into defender's space.
2b. Since you've moved, you provoke an AoO.
3. Opposed STR checks occur.
4.winner stays in the square, loser gets shunted out.