1. Download the plugin bb-attachments.php.zip
2. Unzip and upload to your WPMU plugin directory. Activate it.
3. You’ll have to make a few changes/additions to your theme files to make it work. In your BP theme directory, go to groups/single/forum/topic.php. On line 9, after the ‘template_notices’ hook, add

   <?php do_action( 'topic_page_load' ) ?>

   Next: After line 61, which reads

   <?php bp_the_topic_post_content() ?>

   insert the following line

   <?php do_action( 'bp_after_post_content' ); ?>

   Next: On line 26, replace

   <form action="<?php bp_forum_topic_action() ?>" method="post" id="forum-topic-form" class="standard-form">

   with

   <form action="<?php bp_forum_topic_action() ?>" method="post" id="forum-topic-form" class="standard-form" enctype="multipart/form-data">

4. In the same theme directory, open edit.php and index.php. Find the <form> tags, as described in the last part of the previous step, and replace them with the alternative <form> tag (with the enctype specified)
5. Follow steps 1 and 2 from here. Step 5 on that page (the “optional settings”) you can do as well, and those settings might take some tweaking for certain filetypes to be allowed.
6. Start uploading!

A few caveats:

• I have not tested any of the AWS abilities. It’s possible that they will still work, as the AWS functionality is more or less abstracted from the specific bbPress hooks.
• Inline images are not yet supported. I’m working on it.
• Things look a little bit ugly with the default BP 1.1 theme. I haven’t done much to make it pretty. I’m happy to take aesthetic suggestions, if you have any.

Thanks in advance for your help. Please leave any comments here in this post’s thread.

Related posts:

1. Forum Attachments for BuddyPress
2. New version of Forum Attachments for BuddyPress
3. New BuddyPress / bbPress plugin: Group Forum Subscription