My husband and I loaned family members money to help them buy land and put a down payment on their house. This loan was made 2 years ago and they have just in the last few months started paying us small monthly payments. At the rate they are paying us back, it will take 70+ years to get our money back. I would like to set up legal documentation of this loan and also be listed as a mortgager on their land/home so that if they ever refinance their home and pull money out of their equity, that our loan to them will be paid off in the refinance. How do we go about doing this and attaching ourselves as lienholders?

Have them sign a promissory note. You can get a blank one online or at stationary stores. Modify the note to list the property as collateral for the note. Then take the signed copy to county clerk and have him list that as a lien on the property.

Well for course the time to get the paper work was the day you gave him the money (before you gave it) now you have to go to him and ask him to sign paperwork, what happens if and when he says no he will not sign.
But if he will sign you can do as Scott recommened.