Givens:
DevServerA
DevServerB\\2K5
Problem:
In 4 part names, the first part if the name of a linked server (ie. a metadata object), not the name of a server (ie. a host name). So you can name your linked server FOO and have him point at the host BAR, or at the instance FOO\BAR. And even if you name the linked server object to contain a slash, you can still use it in a multi-part name by simply quoting the name:
SELECT TOP 1 *
FROM [DevServerB\2K5].master.sys.tables