TortoiseSVN: How to supply a port number

The Problem 

I had to access a client's SVN repository through SSH but on a port other than port 22.  I tried specifying the port number at the end of the server name, like the following:

svn+ssh://don@www.theserver.com:20021/rest/of/path

I received the misleading error "no repository found in 'svn+ssh://don@www.theserver.com:20021/rest/of/path'"

How to make it work

I found a solution that uses Putty integration.  Install Putty, run it, and configure a new named session that has the name or IP address of the server as well as the port number that you need to connect to.  Save that session to a specific name, for example "MySession".  The svn+ssh protocol knows about the saved Putty sessions, so that's all you have to do.

Now just go back to your SVN Checkout command and use the session name in place of the server:port designation, for example:

svn+ssh://don@MySession/rest/of/path

I hope this information saves somebody some time.