You can download GUidHost 2.4 for Mac from our software library for free. The software is categorized as Audio & Video Tools.
From the developer:
The GUidHost is a Vst instrument host that allows you to load 4 virtual instruments at the time which can be set on 4 different midi channels. This tool can be useful if you have a sequencer that does not support vst instruments such as Protools, DigitalPerformer or the discontinued but still exellent StudioVisionPro.
You may want to check out more software for Mac, such as Massive Audio Compressor, which might be similar to GUidHost.