Add decimal to MAC Address in Excel

i have a list of MAC addresses in a spreadsheet that currently do not contain any decimals. i would like to painlessly add the decimals in the correct position. the only way that i have been able to figure out so far is to use text to column to split the MAC address into three cells, and then use an add-in called ASAP Utilities to insert a decimal at the start and end of the second cell (from what i can tell, ASAP doesn’t allow you to pick a location in the cell other than start and end). then i have to use a formula to combine all three parts back together.

i know that there has to be an easier way, but i haven’t been able to find it yet.

thanks.