You need root for this full functionality to work without the broadband trick.
There are other threads, in general about this, but this is huge. By using methods by the Droid and other phones, this kid did this with an Eris. I take no credit for this, but I have been hunting for this for a long time, messing with iptables, messing with proxy's and APN's, and have been unsuccessful. This is a modified/fixed (by me) version of what token419 posted on Howard Forums, no longer a direct quote.
This is without the broadband trick (you don't need it), and is good for FULL functionality, just get a Cricket plan that involves 'web'!
Thanks, to token419 from Howard Forums (and those who helped him)
NOTE: All of the things in the following threads must still be done to get your Eris on Cricket FIRST, and to get MMS working (before or after, doesn't matter)
On Cricket to start with:
http://androidforums.com/htc-droid-eris/40266-eris-cricket-wireless.html#post309039 (scroll up and down a few posts for all the info)
MMS:
http://androidforums.com/htc-droid-eris/51990-eris-cricket-mms-wep.html#post432287
At your own risk:
Requirements:
Rooted Rom
Autostart (Root) from android market (free)
u2nl.zip from white rabbits site
whiterabbit.org (hit Android stuff at the bottom, then get the pre-compiled Droid binary - Eris is included in that file)
Following Brandon's Guide and replace the internet portion with the steps listed below
Step 2. Setting up
What you need: u2nl.zip from white rabbits site
whiterabbit.org
install Autostart (Root) from android market
Unzip the u2nl.zip to your androidsdk/tools folder so that u2nl and autostart.sh are in your androidsdk/tools folder. (use the autostart.sh that's in the Eris folder, not the one in the Droid folder!)
adb shell
mount -o rw,remount /dev/block/mtdblock3 /system
cd /data/
mkdir opt
chmod 0777 /data/opt/
chmod 0777 /system/bin/
I can get up to the above part than it say promision denied. Also I have to use SU before it will take any of these commands
So how did you get it working...