Note: It would be greatly appreciated if the person who created this trick could come foward. Also, while this trick is a gray area (because "it relies on being able to define lycanthropes as a new creature created by a template instead of as a creature with a template") I feel it is gray enough to be posted here. "Minor Shape Change keys off disguise self, not alter self or alternate form, which did not receive the same errata.
Racial Emulation allows a Changeling to, when assuming the form of a humanoid creauter (which lycanthropes are), emulate any of that humanoid's subtypes and count as that race for other purposes.
Assume Supernatural Ability allows you to gain use a single supernatural ability of any kind of creature that you take the form of with a polymorph self or similar spell, which supposedly Racial Emulation meets, since you count as being that race by using a spell.
You use Minor Shape Change to take the form of a Werebattletitan in humanoid form, and because of Racial Emulation you count as a Werebattletitan. You then choose their Alternate Form ability as the single supernatural ability you gain from Assume Supernatural ability.
So, supposedly, as a level 1 Changeling with 1 flaw, you can take the form of a 36 HD Battletitan or it's hybrid form."
Edit: Since you need to be within one size category of the battletitan you will need access to dragon so you can emulate the half minotaur template on the character. Half minotaur gives a size category while retaining the original type.
If you don't have access to dragon you can still use the legendary animals from the monster manuel 2 or the cave dinosaurs from the minis handbook. Edit: Gah so confused. I thought I would just be transfering this here and that would be the end of it. I'll just leave this post by Ejothims here and let you guys figure it out 
. I believe it was on the old BG forums that someone explained the templated restriction still applying, though I do not honestly recall it myself.
Perhaps it was defining the race you are emulating?? As, for example, Feral Minotaur is not a race, but rather means "Minotaur race with feral template applied." I honestly do not recall.
If you do find that to be a problem (or someone else points out the reason again), below is a bit more in depth about what that gray area may or may not allow, as well as a final note about why allowing the gray area means templating in order to create a valid base for a Werebattletitan is also not an issue.
To be honest though, this trick first came out so long ago as a mere aside and is so blatantly, obviously, stupidly broken that it was never regarded (even by myself and others who supported it's potentially shady legality) as anything more than a joke... Akin to IHSing away the sun if you're a Drow.
PC: I'm playing a Changeling with 1 flaw and no gear... But I didn't take VoP...
GM: Why not?
PC: You'll see...
The strictest (but most complicated reading) is that there is no such creature as a Werebattletitan. Just a X base creature with the Lycanthrope template used to apply a Battletitan as the base animal. Since you cannot emulate templated forms (even though the ability itself was not given errata, it specifically keys off of things that were), you could not through this reading use this trick.
The gray reading looks at how the Lycanthrope template and other creature combining templates (tauric, etc.) are actually applied. A template used to combine two creature entries to create a third. Tauric (is supposed to) create driders and centaurs, and Lycanthrope does create the Werewolves, Werebears, etc actually listed out as monsters in the entry.
Another possibility, of course, is that within the second reading Lycanthropy creates a subset of templates, each with affects dependent on the base animal used.
IF you go with the gray reading and assume a new creature is being created as the product of the template, that creature stands in it's own right with the stats it has.
So, if you think this could work, it works regardless of whether or not the base creature had to use a template to qualify for acquiring the Lycanthropy template keyed off of Battle Titan as the base creature, as the new creature created as a result is devoid of any templates used in it's creation, though it has all the benefits/penalties of stats of them.
It is a similar concept to how templates can be stacked on both sides of a Tauric creature before Tauric is applied, then onto the Tauric whole afterwards as well.
