EMIR is a NIR multiobject spectrograph with imaging capabilities to be used at the GTC. A general description of instrument performances, as well as the updated optical and mechanical layouts, can be found elsewhere on these proceedings (reference documents 4, 6 and 7). After the successful results of the Preliminary Design Review in March 2003, EMIR optical design is now complete. Some specific features of the optical components make it particularly difficult to mount them in the instrument. For example, the first collimator lens in EMIR is one of the largest Fused Silica lenses ever mounted to work under cryogenic conditions, and some other lenses in the system present features such as aspheric surfaces, tight centering tolerances etc. The analysis of the testing being done in order to validate three different lens mounting design concepts is presented here, as well as the detailed status of the lens mounting design solutions adopted.