Answer

See Application Note AN533, Section 6, steps #1 and #2.
http://www.silabs.com/Support%20Documents/TechnicalDocs/AN533.pdf

This is the bootloader App Note, but the instructions are still applicable. In short:

1. Change the reset vector in the startup code. 
2. Move the interrupt vectors.

More information can be found here:
http://www.keil.com/support/docs/189.htm

Answer

Simplicity Studio allows you to import many project types.  The Silicon Labs IDE creates a project file with the extension <ProjectName>.wsp.  In order to use this project with Simplicity Studio you can follow these steps:

1) From the Simplicity Studio IDE select [File] > [Import...].

2) From the [Import] GUI window select [MCU Project] and select [Next].

3) Browse to the directory where the <ProjectName>.wsp file is located using the [Browse...] button then select [Next].

4) Select the target part for the project using the [Part:] drop down menu.

5) You can leave the default settings for the project and click [Finish].

The project will now be imported into Simplicity Studio.  

Answer

When an example is brought into the IDE from Simplicity Studio > Software Examples, the standard SILABS_STARTUP.A51 startup file is automatically added to your project.

The standard startup file works for all software examples except the bootloader, because the bootloader source contains a customized startup file, boot_startup.asm.

The solution is to delete SILABS_STARTUP.A51 (right click the file > Delete) and rebuild.