Yes.
Described in 4.3 Program Flow of the following manual
Available from URL.
CC2538/CC26xx Serial Bootloader Interface
http://www.ti.com/lit/zip/swra466

After unpacking, you will find the executable file below.
swra466a\sblAppEx_1_02_00_00\bin\sblAppEx.exe

In addition, when rewriting the firmware via UART, the ROM code inside the CC2650 is used, so the pins that can be used are fixed.
See Table 8-2 in the Technical Reference Manual below. http://www.tij.co.jp/general/jp/docs/lit/getliterature.tsp?baseLiteratureNumber=swcu117&fileType=pdf

*This answer is for the manual at the time of Rev.H.
Please note that chapters and drawing numbers may change when the datasheet is updated to a new revision.