I have slightly different requirements and got this working in a different way, although the fine explanations in this thread provided reassurance that it could be achieved somehow.
My LG Optimus Slider is very short on internal storage, so I used the very lightweight "FTPServer" app instead of ES File Explorer, and configured it to only accept connections via my Windows 7 laptop's Connectify ad hoc hotspot. I had some trouble getting Windows to behave when mounting the drive, so I wound up using the username "anonymous" with no password. This is obviously quite insecure, but I rarely turn on the Connectify network and only turn on the FTPserver app as needed, as described below. (BTW, I use port 1026 on my phone for FTP, since that way rooting isn't required).
Let me back up for a moment and explain the problem I was trying to solve. I use B-folders, which is a password management app which syncs locally (usually via USB) rather than through the cloud. Following a recent unnecessary wipe of my laptop (thanks HP, the screen was broken but there was no need for your technicians to touch the hard drive), I am unable to mount my phone as a drive on the laptop, and therefore unable to sync B-folders in the normal manner. I also tried mounting my Nook HD+ tablet, also without success, and was unable to address this problem by repairing Windows drivers.
So I decided to use this Wifi approach, but there is one more problem. It is not that difficult (as described by others on this thread) to access an FTP server through Windows. But mounting it as a lettered hard drive (e.g. G
is more difficult, and this was a requirement for using B-folders. In the end I was able to do this on an ad hoc basis using a Windows application called NetDrive.
For B-folders users, there is probably a cleaner solution to this entire problem, which I discovered after successfully syncing my phone with B-folders, and decided to also sync my Windows B-folders with my tablet. This tablet dual-boots in a native (unrooted) environment as well as an alternate ROM environment which is rooted. I decided to sync B-folders both ways using FTPserver, and discovered that the when using the rooted tablet, Window's B-folders also presented a "peer" syncing option via a TCP port.
So perhaps I could have avoided much of this pain by rooting my phone instead, but I am not certain of the details.
Sorry for the novella-length post, but hopefully someone will find this useful someday.
Thanks again to the original posters.