I haven't found one yet.
The problem is that when you select multiple rungs, RSL5K copies them to the clipboard in Neutral Text mode ("XIC(Bit1)OTE(Bit2)") instead of the SLC-friendly ASCII mode. ("XIC Bit1 OTE Bit2")
You can try and selecting multple rungs (using the shift and/or control keys to assist), pasting them into Notepad, and then doing a search/replace:
open paren, close paren ==> space
semicolon ==> "EOR SOR "
left bracket ==> "BST "
right bracket ==> "BND "
You get into trouble with the comma. It's used both as a "Next branch" (NXB) and as a delimiter between numerical values in blocks ("COP(A,B,C)", and so could also go to space.
But if you're careful, you CAN do it.
Also, there's no need to search/replace on the tag names. If you have the SLC address programmed with a SYMBOL name that's the same as the existing CLX tag name, the logic will import without error. Just edit your Address/Symbol database ahead of time (a CSV import is great for this).
Good luck!