Since it was first introduced in 1986, AutoLISP has been a mainstay for users working with AutoCAD. Inventor utilizes Microsoft Visual Basic for Applications (VBA) as its extensibility language. Because of the syntactical differences between LISP and BASIC, and the database schemas and application programming interface (API) differences between AutoCAD and Inventor, there is no reliable means of automatically converting AutoLISP to VBA is practical.
Many AutoLISP routines are used to automate the creation and editing of commonly used geometries. Inventor provides built-in functionality for automating the creation of features, parts, and assemblies that are used repeatedly. While not intended to replace AutoLISP, consider the capabilities of iFeatures, iParts, and iAssemblies in cases where they apply.
Like the AutoCAD User Community, Inventor users have been actively extending their productivity by creating and sharing VBA add-in applications. It is possible that user-created solutions exist that can replace your regularly used AutoLISP routines.