Can he wipe over his khufoof when removing madhiy (prostatic fluid)?

Firstly: 

Madhiy is najis (impure) and nullifies wudoo’ according to
scholarly consensus. 

An-Nawawi (may Allah have mercy on him) said: The ummah is
unanimously agreed that madhiy (a fluid which is usually secreted as a
result of sexual excitement) and wadiy (a thick white fluid that may come
after urination or due to other reasons such as illness) are najis.

End quote from Sharh al-Muhadhdhab, 2/571 

And he (may Allah have mercy on him) said: Ibn al-Mundhir
said: They are unanimously agreed that it (wudoo’) is invalidated by the
emission of stools from the back passage, of urine and madhiy from the front
passage, and of wind from the back passage.

End quote from Sharh al-Muhadhdhab, 2/6 

Secondly: 

What is required when purifying oneself from madhiy is two
things: 

1.To wash the penis and testicles
to remove whatever has gotten onto them of madhiy, because of what has been
stated above of it being najis.

2.To do wudoo’ to purify oneself
from it when wanting to pray or to do anything for which wudoo’ is
prescribed, because madhiy is one of the things that invalidate wudoo’, as
stated above.

See also the answer to question no.
2458 

With regard to washing off the traces of madhiy, this
requires washing the traces from the affected part of the body; it cannot be
imagined that this involves wiping over the khufoof, as is quite obvious. 

As for doing wudoo’ because of madhiy, it is like doing
wudoo’ in the case of any of the other things that invalidate wudoo’. If the
individual put on his khufoof when in a state of purity, it is permissible
for him to wipe over them when doing wudoo’, because of the hadeeth of
Safwaan ibn ‘Assaal (may Allah be pleased with him) who said: The Messenger
of Allah (blessings and peace of Allah be upon him) used to command us not
to take off our leather slippers for three days except in the case of
janaabah, but not in the case of stools, urine or sleep.

Narrated by at-Tirmidhi, 96; Ibn Maajah, 478; and others.
Classed as saheeh by al-Albaani in Mishkaat al-Masaabeeh, no. 520 

This indicates that wiping over the khufoof is permissible in
the case of things that invalidate wudoo’. But in the case of janaabah
(impurity following sexual activity), that requires ghusl so it is not
permissible to wipe over the khufoof when purifying oneself from it.