OK, here are more specifics. This is about 2 different cables.
First one is for a serial application that is not working properly. The devices connect through 4-pair CM UTP cable with 8P8C rj45-size connectors wired as RS232 serial. The manufacturer of the device suggested shorting 2 of the conductors to fix what they think is a handshake problem. I can splice the wires, no problem. I can also solder them together. But I was wondering if there was a less messy way, like a modular plug with configurable shorting bars or something in that vein. There ARE so-called jumper adapters, such as this one that I could use. That would mean going from RJ45 to DB25 and back - not a pretty sight.

Second question: customer has a Leviton 24-port rackmount voice panel. Connects to devices through 8P2C rj45-size connectors, wired as rj11. Connects to the PBX through a 50P/48C amphenol connector (pair 25/50 in the amphenol is NOT wired). Regular Telco Cat3 25pair patch cable is used. This application requires use of pair 25/50, but several other amphenol pairs are NOT used by the application. I want to jump the 25/50 pair to one of the pairs that are NOT used by the PBX, but ARE wired on the panel, so I can connect the device relevant to the application to a rj45 port. I was wondering if there's a way to this again avoiding splices or soldering either at the patch cable or at the customer's voice panel. As I mentioned above I'm leaning towards using the AMP wear adapter and their insertion/extraction hand tool (put in an order for both) and then do the do at the adapter. But any ideas are welcome.