another way, use a midi foot controller with free looping program like sooperlooper (
http://essej.net/sooperlooper ) or mobius (
http://www.circularlabs.com )
On mac, theres also mainstage2/3, together with an apogee gio, looping cum all guitar needs be within the comp.
On the other hand, just wondering, between the guitar and the ux 2, are there physical effect pedals, di box then to the ux2 or just guitar straight to ux2 and all processing/amp sim are done within the computer then output from ux 2 to speaker?
If its the former, can just pop a looper in the usual chain. If its the later, it might be tricky on the impedance matching side, line level/instrument level matching or even matching the connection plug type of the looper and the ouput of the ux 2.
Oh well, either way, no harm trying and prolly wont damage anything. Have fun!
oh yeah, on clicking issues on computer, imho, with today computer or even few years back series, the clicking/noise issue can be solved as long as theres proper separation of drive meant for music and leisure plus some tweaks which can be one.