To add a file extension to have a bundle autoloaded for it. You would go to the file:
C:\Program Files\e\Bundles\blah.tmbundle\Syntaxes\blah.plist
And add an entry under:
<dict>
<key>fileTypes</key>
<array>
<string>html</string>
<string>htm</string>
<string>shtml</string>
<string>xhtml</string>
<string>phtml</string>
<string>php</string>
<string>inc</string>
<string>tmpl</string>
<string>tpl</string>
<string>ctp</string>
Restart e and you are done.
Change File Associations in E-TextEditor