Hello,
you have two options to do that.
1. Use the primary and secondary mapping
These 2 mappings are working at the same time. So you do not need to switch from different configs.
Do not change the default settings in primary mapping.
Then set L1 and R1 to a same button of KB or MS in the secondary mapping.
That should work.
2. use Macro
just add L1 and R1 in one line of Macro,
and choose a hotkey for that Macro.
It's also very simple.
For more info about Macro usage, please visit here:
http://www.reasnow.com/forum/index.php?topic=1710.0