As of IGB 10.1.0 most UCSC genome versions and tracks are available by default in IGB via the UCSC REST data provider.
UCSC Genomes in IGB
Genomes available from UCSC should automatically appear within the Species menu.
UCSC Tracks in IGB
When a genome is selected that has UCSC tracks, a UCSC REST folder will appear in the Available Data sub-panel of the Data Access tab. Open the folder and select a track to add it to IGB.
Troubleshooting
If you do not see genomes or tracks available from UCSC, check the Data Sources tab and make sure that UCSC REST is set to Enabled.