My experience with C/M is with the Enochian system primarily the Hepatarchy. I'm a grimoirist and don't use the G/D or any associated methodologies. My focus in the system has been the 1st 5 books of mystery and other obscure and understudied areas such as Liber Logaeth and Arney vah nau. I do have some minor cabalistic background, and gardianarian, but we're going wayyyy back with that. I also did servitor magic before Enochian as well.
A number of practitioners who I associate with have long suspected a link between the Hepatarchy and the otherworld; in particular Bynepor the angel king of Thursday's description in the 4th book of Mystery gives a strong indication of a probable otherworld link. A suspicion that at least in my own mind I now believe to be correct, and it was he that probably dumped my unsuspecting headfirst into working with the Sidhe. There was nothing gentle or fluffy about the introduction. Scared me out of my wits to be honest with you.
How other grimoires relate to the Sidhe depends on how you view who they are. If your view is the relatively recent belief that they are fallen angels but not as evil as demons, then the grimoiric magic techniques would apply ….. personally I say good luck with that and make sure that I'm not anywhere near you when you try. The possible exception being the techniques of Grimoire Vernum particularly those subscribed to by Stratton Kent which is a much more respectful approach and the use of pacting techniques are relevent and applicable. Use of talismans as the MM for the pact might be an idea worth tryinhg.
Mediumsitic techniques seem to be a more acceptable means of invocation and the I believe its the 20th and 21st call of Arney vah nau that I initially used in a respectful invocatory way it was well received and yielded results. This however was in my responding to request by the sidhe. I don't know of anyone who has tried full posession techniques such as the Santeria and Voodou practitioners use, however I would think that would be a highly effective means of working. partial posession mediumism is used. I'd really like to see those techniques tried.
Talismens are used and some are found on this site if you take a look. Also if you look at Ashmoles formula you'll see a traditional evocation. I strongly discourage forced evocation except in unusual circumstances such as a spirit assaulting someone and a resolution is not possible any other way.