IO, it depends on the runway braking action, but at my company we have a sliding (pun intended) scale which ends with a 10 kt crosswind after starting at 35. Runway length also has to be calculated based on the braking action report which is supposed to be included in the ATIS any time it goes below o.40.
In a previous existence, as a Safety Board investigator, I was called out to investigate a DC-10 which slid off the end of the runway. He had decided to land based on the report "Previous aircraft reports braking action Fair" from the tower. Trouble was that the previous aircraft was a Piper Aztec. So personally I don't put much faith in pilot reports unless I know the aircraft type.
If you care to search in the McDonnell Douglas archives, which are probably now with Boeing, there is an excellent article in the Tri-Jet newsletter from about 5 years ago which addresses landing on slippery runways. The explanation of the pitfalls of using reverse thrust in slippery conditions is absolutely spot on.
As advice, use the best info you can get to make the calculations, and if you have ANY doubts then fudge it to the good side and go elsewhere. Life is too short to waste time in a snowbank.