Well for one, you should post this in the forum that's... you know... dedicated to MDMA.
Secondly, yes, you can do it, but it's not very recommended. A dose can be up to 3 or 4 times stronger than if you would have taken it orally, so DO NOT use more than 30mg at first... you might even want to go lower than that.
Expect to be disappointed, not many people like IV MDMA. Most say it lasts way too short and is too fiendy since the roll lasts a half hour at the most, and others say it's far too intense of an experience to be enjoyable. I would advise you to reconsider... plugging is probably much better than injection, it will give you a rush, but will last a lot longer than IV as well