There's a way to do this but it requires a little preparation on your contact list. If you update a contact with a bridge number and access code, you can add the access code to the "Description" field of the calendar event. The calendar app hyperlinks the access code to the phone dialer. At least it does on my VZW S3. Another option would be to create contacts for each bridge/code combination you use frequently. Yet another option would be to include just the bridge number in the description. Tapping the bridge number will bring up the dialer which then presents an option to choose from your contact list any contact that has that number associated with it - just select the contact with the access code you want to use.
These approaches work well with static bridge codes.
For example, I have several conf bridges defined in my contacts list with their numbers defined as: "(800) XXX-XXXX,,12345678#" where "12345678" is the access code. The ',' indicates a soft pause and the access code is sent automatically after a brief pause. You can adjust the length of the pause by adding/removing ',' characters. If you need a hard pause (you'll be prompted to send the subsequent tones), use a ';'.