There is more than one way to do this, I will tell you what works for me. The key is do not skip a step. First go here
http://xdaforums.com/showthread.php?t=1524081 and do step one. Once completed, go to download mode again and flash bootloaders. Next go to post 2 and get Entropy's Daily Driver. All credit for this to qkster for providing an easy to follow process that has saved many of us numerous times and Entropy512 for the kernel.
At this point you should have a working stock rom with red CWM recovery. Rather than jumping straight for miui v4, I highly suggest an extra step, go and get
http://xdaforums.com/showthread.php?t=1601844
Download the 6/27 version and again follow his installation instructions- note that it is normal on first install to get stuck- instructions will get you out- all credit to Entropy512 for this fine work. Let this boot- you do not need to set up anything, just keep skipping through setup until it is complete. Leave your phone on for 5-10 minutes as the rom "settles." And now go here
http://roms.miui.us/
go to the Infuse and download 2.7.6. Wipe data,cache, and dalvik and install miui. Should be smooth sailing from here. Anything else let me know.
Edit: After you have 2.7.6 up and running you can get 2.7.13 and just wipe cache and dalvik and be good to go. 2.7.6 performs better. This is a guide of what works for me -you may have different results. I am not responsible should anything result other than the intended outcome.