You can build it with a "simple" developer account but it would be worse since it's limited to 100 devices.
There are other ways, but which involve jailbreaking so well, let's say that's not doable at an enterprise level and anyway doing this you couldn't use the "push" alerts.
Actually, you have to generate quite (say, a lot) of certificates (push, delivery, developer) certificates to build the .ipa, all those are linked to your "enterprise Apple" account.
Then people connect to a web page, click on a link and download / install the IPA automatically.
You'll need at least a "developer account" to sign application, and the proper way to get the certificates and stuff.
Perhaps support has the way to do that with a simple developer account.
Without certificates, you can't generate the IPA so well... Or perhaps you could ask BMC if they have a "demo" IPA but I doubt it since in that case it would use their "push" certificate.