Nope. Just do ##778 and enter all the settings, as in the Ryan Mogul thread. Also, download some cricket .prl files to try. Put those .prl files on your SD card (anywhere), and when you enter all of THESE settings, also make sure to update the .prl file (you'll see).
http://forum.xda-developers.com/showthread.php?t=492824
Then take your Eris to the cricket store, and tell them you 'got your phone flashed'. Let them scan your phone, and *228 will work at this point. Your phone is now on Cricket.
Then, for MMS to work, use APN Backup & Restore, available from market. Backup your APN file twice (because one of them you're going to edit). Mount your SD card on your computer. Right click one of the .xml files in there, and hit 'Edit' (in Windows). Then in the 'Production' area (you'll see), set the user, password, mssproxy, mmsport, and mms server as follows (just copy these settings over, and put your phone number in there)..
http://androidforums.com/432287-post9.html
Once you've edited and saved your .xml file (make sure you remember which one you just edited, maybe rename it when you're done?), then unmount your SD card from your computer, and on your phone, open up APN Backup & Restore.
Delete APNs.
Restore APN (choose the one you just edited).
Restart your phone.
Download AnyCut from Market, and make a new shortcut for 'Proxy'. To use your mobile web, set your 'Proxy' to wap.mycricket.com port 8080. Your web will work. Other internet stuff (like Market) won't, unless you're within WiFi. If you're using WiFi, open the 'Proxy' shortcut back up (that you created) and delete the proxy and port settings (so that they're blank) and save, to use the web and internet.