the first responses are the correct (and practical) recommendations, but since I had a similar issue last year I did some experimentation. I ran a 2 meter RCA connected in line with my phono cable using F/F rca adapters (which has to be the worst way to do this). This gave me a 3 meter length to the phono input on my preamp's inboard phono section. I was pretty content with it, but didn't do any really critical listening at the time, nor was I using a top line table/cartridge with this setup. It was a perfectly acceptable setup IMO, though if you listened carefully there was a little more noise. I was still pleased with my vinyl.
I also ran a similar setup but using an outboard phono preamp, with a 3 meter ic from the phono to the linestage preamp. Except for some special grounding I had to install, the result on this was better, and probably will stand up to more critical listening.
net/net - I suggest you try it out and see how satisfied you are with your own setup. I doubt you have anything to lose but the time it takes you to set it up. I certainly think you'll be more satisfied with the sound of a phono with 3M ic's than no phono at all.