Hi Robert,
If you are familiar with program such as After Effects & Photoshop, creating animated transitions is not too difficult. When you make an animation for use as a media wipe it would normally start off screen - then animate to full screen and then off again. Once you have the animation you simply need to render it as a 32bit TGA sequence (premultiplied Video with alpha channel) then transfer the sequence to the media store. If you are not familiar with graphics animation programs then there are quite a number of libraries where you can get pre-made animations for this purpose.
I dont know all of the sources, but look up Digital Hotcakes or Digital Juice (no affiliation) and you will find a lot of choices, if you decide to use them just be sure to get them in the correct screen resolution for your production. They may also need to be converted to TGA sequences, but normally they supply a simple conversion app for that if you buy from them.
I hope this helps - MediaWipes really can add tremendous value to a production, good luck.
Nigel
#Carbonite