A strike made with a two-handed weapon can push a similar sized opponent backward.Prerequisites: Str 15, Power Attack, base attack bonus +1.
Benefit: When you hit a creature your size or smaller with a two-handed weapon attack modified by the Power Attack feat, you can choose to push the target 5 feet directly away from you instead of dealing the extra damage from Power Attack. If you score a critical hit, you can instead push the target 10 feet directly away from you. This movement does not provoke attacks of opportunities, and the target must end this move in a safe space it can stand in. You choose which effect to apply after the attack roll has been made, but before the damage is rolled.
Emphasis mine.
You gain the feat without needing the prerequisites however the benefit of the feat only affects attacks modified by Power Attack, so it wouldn't do anything unless you had Power Attack. Ranger will let you bypass the Str 15 requirement though, for those Weapon Finesse using Power Attackers out there.
Yeah, necro.
Still it shows I did my homework and searched the forum :-)
Also this thing is actually ancient so there might have been FAQs or erratas...
Basically what the OP asked, perhaps with the following option:
You don't have power attack, so you can't make one. You could still incur the respective penalty and get only the push back effect. Of course this isn't RAW and most propaply also not RAI.
Still would it seem highly unbalanced to use the option?
I'm aware that at level 6 a Ranger gets another bonus feat free of prereqs. But two levels of ranger are already almost too much for my taste :-(
If there are no possibilities I'll try for a trip build but this is another thread :-)
Shameless bump
Unbalanced? No, it seems fine as a house rule.
Personally, I'd just take Power Attack...