All the instructions are available here:
http://gentoo.ovibes.net/nautilus-share/

The following is a quick rip from the wiki.

===Source code (0.7.x only)===
* Version 0.7 require samba 3.0.23, you need to configure samba to work with "net usershare"
** [http://gentoo.ovibes.net/mate-file-manager-share/mate-file-manager-share-0.7.0.tar.gz mate-file-manager-share-0.7.0.tar.gz].

* Here are the info from the samba's[http://samba.org/samba/docs/man/manpages-3/net.8.html net] command to setup '''usershare'''
<pre>
USERSHARE

Starting with version 3.0.23, a Samba server now supports the ability
 for non-root users to add user define shares to be exported using the
 "net usershare" commands.

To set this up, first set up your smb.conf by adding to the [global] 
section : usershare path = /usr/local/samba/lib/usershares Next create
 the directory /usr/local/samba/lib/usershares, change the owner to 
root and set the group owner to the UNIX group who should have the 
ability to create usershares, for example a group called "serverops".
 Set the permissions on /usr/local/samba/lib/usershares to 01770.
(Owner and group all access, no access for others, plus the sticky 
bit, which means that a file in that directory can be renamed or 
deleted only by the owner of the file). Finally, tell smbd how 
many usershares you will allow by adding to the [global] section
 of smb.conf a line such as : usershare max shares = 100. To 
allow 100 usershare definitions. Now, members of the UNIX group
 "serverops" can create user defined shares on demand using the
 commands below.

The usershare commands are:
net usershare add sharename path [comment] [acl] [guest_ok=[y|n]] - to add or change a user defined share.
net usershare delete sharename - to delete a user defined share.
net usershare info [-l|--long] [wildcard sharename] - to print info about a user defined share.
net usershare list [-l|--long] [wildcard sharename] - to list user defined shares.
</pre>

====Compilation from sources====
* You need the following dependencies:
** mate caja 1.1
** libglade
** gtk+

* The common procedure as root:
<pre>
./configure --prefix=/usr
make
make install
</pre>

====Setup and configuration (apply to Ubuntu Feisty and Gutsy)====
* A  quick and easy wait to have it running (must be done as root):
<pre>
export USERSHARES_DIR="/var/lib/samba/usershare"
export USERSHARES_GROUP="samba"

mkdir -p ${USERSHARES_DIR}
groupadd ${USERSHARES_GROUP}
chown root:${USERSHARES_GROUP} ${USERSHARES_DIR}
chmod 01770 ${USERSHARES_DIR}
</pre>

* use the following '''/etc/samba/smb.conf''':
<pre>
;/etc/samba/smb.conf

[global]
workgroup =  WORKGROUP ; you can change to your own workgroup
security = share

usershare path = /var/lib/samba/usershare
usershare max shares = 100
usershare allow guests = yes
usershare owner only = yes
</pre>
* Add the samba group to your user (replace your_username by your login):
<pre>
usermod -a -G ${USERSHARES_GROUP} your_username
</pre>
* Logout and login
