aMember / vBulletin simultaneous login
 

I'm trying to get my users to be able to sign in to aMember and vBulletin simultaeneously, from the aMember login page. So far I haven't found any plugins that can pull this off, so the few ways I'm thinking about going about it:

Modify the aMember login page and add hidden fields that will pass to whatever file handles vBulletin logins

Modify the actual aMember login.php, pick up the user/pass and pass them through to vB.

Are there any problems with either of these methods? If not, how would I go about sending vB the info?