Two iTunes accounts on one computer > one iPad

Hi,

In our house we have an iMac with two user accounts on it - my account and my wife's. We have separate iTunes accounts, and share music between them. We have recently bought an iPad, which is synced to my iTunes account. However it's a shared machine so we would ideally like to be able to access both iTunes libraries from it. Is this possible, and if so how do we go about it without having to merge our music collections together (something we'd rather not do, as we have different tastes)?

I know iPads aren't ideal for multiple users, but surely there's a way to do this?

Thanks!