Andreas, Hi:
The following link is for the Expression Language and the related functions.
http://wiki.jriver.com/index.php/Expression_LanguageI do not see any functions which will alter COLOR or HIGHLIGHT string values. In particular, look at the string manipulation section. The functions are limited. However, here is a suggestion based on my experience with the Expression Language. You could change the case of specific values in an effort to highlight the desired values. This does not address your specific question but it does give you some idea of how to manipulate text in a rudimentary way and give you a little experience with the Expression Language.
I have created an additional column in my view called 'Highlighting Test'. I initiated this by right-clicking the header for any column. I then selected 'Add Expression Column...'. I added the following expression: if(isequal([Genre], pop/, streetcorner,1), FixCase([Genre],3), [Genre])
This expression will change the case of the target field, in this case [Genre] to Uppercase when the [Genre] value is 'pop, streetcorner' (see images). Also note the use of the escape character (the forward slash). This allows me to treat the embedded comma in the [Genre] as part of the comparison value. Compare the values in the two columns to see the difference: 'Genre' and 'Highlighting Test'.
Another alternative might be to add a prefix to a [Genre] (remember, this is just for viewing purposes) such as 'Special' or '***'. You could then sort the column to separate your chosen values. These are just some thoughts for inspiration. Let me know if this helps.
Cheers,
Lawrence