Yup, I've give it a shot in a few sims, Jane's F/A-18 and Falcon will let you do it properly with all the calculations for a proper 'Loft' of course, but I also do it by hand in WoV with the A-6 Intruder sometimes. I've found that a 4G pull up is best, and this was apparently what was used a lot of the time in real life, so I guess that makes sense.
Without guidance of any kind, it's only any use with big area targets and multiple releases though, so I usually set a fairly long ripple delay and a pack of about six bombs (which you could do manually), releasing early and walking them across the target. You'll need to practice pulling up and releasing over level ground at a set distance from the target and at a set altitude (I use 200 feet before the pull up), and a set speed too. And bear in mind that undulating terrain affects the distance the bombs hit at too, as it does in real life, and was also a problem with the Intruder when it used OAPs (offset aim points). In real life a multiple release like that would be risky as the bombs might collide and go off, which is actually how many of the first A6 Intruders in Vietnam were lost.
I've found success is marginal to be honest, although I did hit very close to the Paul Doumer Bridge in Hanoi once doing it that way (right in the water alongside it), but unfortunately it didn't drop, as it probably wouldn't have in real life, being an open iron structure which would let the blast through.
Don't feel you are cheating to use hud info and stuff if trying it in IL2, because in the sim you lack the sensory feedback you'd have in a real aircraft letting you know how many Gs you were pulling and stuff like that.
Chock