This is probably the same issue with warrior/clerics using healing cycle on themselves during PvPs. I use this all the time during pvp.

I use the "Recent Target" button, but it really only works when you're doing a 1v1. Before you start the pvp, click yourself first. Then click your opponent and start attacking etc etc. When you need to cure yourself, click whatever button you assign to "Recent Target", which will make you target yourself, then you can cure, and once you've done it click the "Recent Target" button again and it will re-target your opponent.
This works very well if you're not lagging, but if you are lagging you could just click your character icon in the top left corner, which makes you target yourself immediately, but that requires using the mouse

Hope this helps.