http://forum.image-line.com/viewtopic.php?t=123031
DropBox
Mac
Win
Add IL Minihost Modular.vst to your VSTi list
Load Load IL Minihost Modular.vst on a track
In MiniHost File > Preferences > Scan vst/au folders
Right click to add AU plugin
Right click yellow/green connections to remove
Drag to connect yellow audio/green midi
Drag connections up/down for level

This is RealGuitar outputing audio to Amplitube guitar amp modeler.

Another way, though not free, but if you have it is Blue Cat's PatchWork
http://www.bluecataudio.com/Products/Product_PatchWork/
there are Demo Downloads on the right.

