Cyclone V HSMC Lvds differential pairs direction

Did you read the specification?

http://www.altera.com/literature/ds/hsmc_spec.pdf

When operated in LVDS mode, the signals are unidirectional, and hence the naming convention.

If you are making a custom system where you do not need to interface to any other HSMC boards, then you could re-define the HSMC LVDS TX lanes to be RX. However, if your system is custom, then just select a more appropriate connector solution. HSMC is not an industry "standard".

You might want to consider using FMC. FMC was a Xilinx idea, but at least its now a VITA standard (VITA 57).

http://www.vita.com/fmc

"FMC HPC connector provides connectivity for 160 single-ended or 80 differential user-defined signals"

The Arria V Development Kit has an FMC connector

http://www.altera.com/products/devkits/altera/kit-arria-v-gx.html

Cheers,

Dave