<p>I've been spoiled by Visual studio 2008 and Eclipse and have to do a little maintainence work on a VB6 app.</p>

<p>Does anyone know of an alternative/ updated IDE for VB6?</p>

<p>A rewrite is not an option I'm just fixing a couple of bugs and it's a big codebase.</p>

Some time ago I did some research and nothing came up. I don't believe you have have any real alternatives...
But you could consider checking this out:
http://www.axtools.com/products/cs2k3vb_screenshots.htm
It looks quite promising.
Addin for Visual Basic 6.0 packing more than 50 professional tools and
  assistants. The Code View Assistant
  enriches the standard VB6 code editor
  with branch lines for conditional
  statements, end-of-line details, and
  hotspots. Moreover, the Code Analyzer
  pinpoints dead and slow code, the
  SmartComplete and AutoText tools help
  you write code with a proficiency you
  never dreamed of, while the Enhanced
  Project Explorer with expanding code
  and Code Flow View can make accessing
  a code location the speedy action you
  always needed. Other tools: Extended
  Find, Find References, Designer
  Explorer, Code Formatter, TabOrder
  Designer (with auto-order), HotKey
  Designer, Error Handlers Inserter,
  Exception Protection, Spelling
  Checker, Strings Reviewer, Comments
  Conformity Checker, Task List Manager,
  Code Snippets Manager, Naming
  Standards Manager.Version 2007 adds
  Designer Analyzer, User Interface
  Standard Properties Manager, Library
  Explorer including Designer Snippets,
  many enhancements in most subsystems.