Bill,
We do not provide intrinsic support for third party plugins but we will surely assist you in this case.
1. You can choose between Subclipse and Subversive plugins for SVN functionality. Here is the link which discusses the advantages and disadvantages of both :
http://stackoverflow.com/questions/61320/svn-plugins-for-eclipse-subclipse-vs-subversive
http://stackoverflow.com/questions/185486/which-eclipse-subversion-plugin-should-i-use
2. If you want to install the Subversive plugin, here are the steps :
a) Switch to MyEclipse Configuration Center > Software. Right click on Subversive plugin under Quick-Add Popular Plug-ins section and select ‘Add to Profile’.
b) When the dialog displays to ask about optional software you can select the two JavaHL items from the related list presented.
c) Apply this change, on restart, depending on your configuration state, you may be presented with additional changes. Apply these changes and restart.
d) Test the environment by opening the “SVN Repsonitory Exploring” Perspective
3. If you want to install Subclipse 1.6 plugin, the select Subclipse 1.6.x from the Quick Add Popular Plugins section, select the components which are marked required and follow the wizard.
4. Please take a look at these links on how to convert CVS history to Subversion :
http://www.novell.com/coolsolutions/tip/18087.html
http://www.ehow.com/how_7562317_convert-cvs-repository-svn.html
I suggest you check on development forums for better support on the migration issues.
Let us know if you see any issues.