This year's test will include Automatic Link Establishment. Yes, this is legal for hams to use, and there is an HFLINK net that does just that. The only hard part is transmitting, since antenna match has to be retuned very quickly by the standards of amateur gear. Good autotuners are essential.
Receiving in scanning mode, though, can be done with plain old PC-ALE. Create a .qrg file of the mil frequencies, and off you go.
From the announcement:
ALE IN USA ANNUAL ARMED FORCES DAY CROSS-BAND
COMMUNICATIONS TEST (09-10 MAY 2015)
= Armed Forces Day ALE Direct Interoperability =
This is the first year that ALE will be in use for this event.
Ham operators may use ALE "Individual Call" selective calling
to connect with a military station, for voice communications.
Amateur Stations with Automatic Link Establishment (ALE)
capability can contact a military station directly on specific
half duplex “cross band” channels established for this purpose.
Military stations will scan and receive certain Amateur
HFLINK ALE frequencies, and transmit on the corresponding
military ALE frequency. Military stations will also
transmit ALE station identification (soundings) on each
military frequency at 30 to 90 minute intervals. Amateur
stations which are capable may scan the military frequencies
and monitor the soundings to build the LQA database or
select the channel manually. HF Radios with an embedded
ALE feature, or ham radios with computer-based PC-ALE,
are compatible for use with the military 2G-ALE used in
this event.
============================
ALE Military Stations:
CALLSIGN | ALE ADDRESS
AAZ | AAZ
NBL | HMBNNN
NUW | NUW
AGA2SY | 2SYAGA
============================
Armed Forces Day Interoperability
ALE CHANNEL FREQUENCY LIST:
Channel| Amateur | Military
X75US | 3,996.0 USB | 4,000.0 USB
X60INT | 5,371.5 USB | 5,385.5 USB
X40US | 7,296.0 USB | 7,357.0 USB
X20INT | 14,346.0 USB | 14,846.0 USB
X17INT | 18,117.5 USB | 18,272.5 USB
X15INT | 21,432.5 USB | 20,940.0 USB
X12INT | 24,932.0 USB | 24,858.5 USB
Upper Sideband (USB) is utilized on all frequencies
for transmit and receive.
============================
Amateur stations seeking more information about ALE go to
http://hflink.net http://hflink.net
============================
ABOUT THE ANNUAL ARMED FORCES DAY CROSS-BAND MILITARY/AMATEUR
RADIO COMMUNICATIONS TEST (09-10 MAY 2015)
The US Army, Air Force, Navy, Marine Corps, and Coast Guard
are co-sponsoring the annual military/amateur radio
communications tests in celebration of the 65th Anniversary
of Armed Forces Day (AFD) and the 90th Anniversary of MARS.
The annual celebration is a unique opportunity to test two
way communications between Amateurs and military communicators
authorized in 47 CFR 97.111, and features traditional military
to amateur cross band SSB voice, Morse Code, practice using
legacy interoperability waveforms, as well as an opportunity
for Amateurs to utilize more modern military communications
modes such as MIL-STD Serial PSK and Automatic Link
Establishment (ALE). These tests give Amateur Radio operators
and Short Wave Listeners (SWL) an opportunity and a challenge
to demonstrate their individual technical skills, and to
receive recognition from the appropriate military radio
station for their proven expertise. QSL cards will be
provided to those stations making contact with the military
stations.