[Plugin: Events-Manager] adding instructions on custom attributes?

hi

i’ve got my attributes working just fine (love events-manager for its amazing flexibility) but one little hurdle i’ve bumped into is this:

HOW can i add some instructions to the user for specific attributes?
eg. for a custom url – #_ATT{Registration URL} – i need to tell them one way or the other to include http:// or not… i can code it accordingly, but how to i add that note to the actual field on the submit event form??

so, perfect world it would display:
Registration URL: {formfield here} include http://

i tried the secondary keys to include http:// in the actual field itself but that only worked as far as displaying http:// if nothing was entered in the field by the user.

any help would be appreciated.