You can use Tcl variables with timing exceptions to accomplish the same effect as an INST/TNM and a TIMESPEC. The following example illustrates the point.
UCF Example:
INST "DUT/BLOCK_A/data_reg[*]” TNM = "from_data_reg_0";
INST "DUT/BLOCK_A/addr_reg[*]” TNM = "from_data_reg_0";
INST "DUT/BLOCK_B/data_sync[*]” TNM = "to_data_reg_0";
INST "DUT/BLOCK_B/addr_sync[*]” TNM = "to_data_reg_0";
TIMESPEC "TS_MCP" = FROM "from_data_reg_0" TO "to_data_reg_0" TS_FSCLK * 3;
Tcl Equivalent:
set from_data_reg_0 [get_cells {DUT/BLOCK_A/data_reg[*]\ DUT/BLOCK_A/addr_reg[*]}];
set to_data_reg_0 [get_cells {DUT/BLOCK_B/data_sync[*]\ DUT/BLOCK_B/addr_sync[*]}];
set_multicycle_path -setup 3 -from $from_data_reg_0 -to $to_data_reg_0;
set_multicycle_path -hold 2 -from $from_data_reg_0 -to $to_data_reg_0;