Integrate PHPBB3 with MODX

I just updated one of my posts as well ha!

Well I use FDM to allow users to create their own profile page and it’s only accessible via username and password.  Each member gets their own page on sign up and is auto generated using a plugin (thanks Dimmy) and it would be awesome if the user could simply go from forum to modx without having to sign in or register twice. 

I use SMF as well and have done since I joined the MODx community... If there was a way to have users sign up to modx and pass the username and password to SMF that would be a start. I would rather MODx handled the users rather than SMF as I would like to have more control over what the user can access in MODx since all they will be doing on the forum is posting.

Okay I’m relatively new to modx, this is my first experience with the system so I’m a bit confused. I have made a new snippet called: AutoSizeiFrame. (The snippet has following content: http://www.keilstruplund.dk/AutoSizeiFrame_0.1.txt)

Now what is next step? Do I simply insert this on my modx site?:
[[AutoSizeiFrame? &iframeids=ID_ViewportWidget_1,ID_iframe_2]]

..but where is the link to the forum I want to be contained inside the iframe then?

You can usually get more help to resource usage from its support thread. For AutoSizeiFrame, see especially this post.